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Effective models focused on pertinent low-energy degrees of freedom have substantially contributed to our qualitative understanding of quantum materials. An iconic example, the Kondo model, was key to demonstrating that the rich phase diagrams of correlated metals originate from the interplay of localized and itinerant electrons. Modern electronic structure calculations suggest that to achieve quantitative material-specific models, accurate consideration of the crystal field and spin-orbit interactions is imperative. This poses the question of how local high-energy degrees of freedom become incorporated into a collective electronic state. Here, we use resonant inelastic x-ray scattering (RIXS) on CePd3 to clarify the fate of all relevant energy scales. We find that even spin-orbit excited states acquire pronounced momentum-dependence at low temperature-the telltale sign of hybridization with the underlying metallic state. Our results demonstrate how localized electronic degrees of freedom endow correlated metals with new properties, which is critical for a microscopic understanding of superconducting, electronic nematic, and topological states.

Background: Compared to commonly-used green space indicators from downward-facing satellite imagery, street view-based green space may capture different types of green space and represent how environments are perceived and experienced by people on the ground, which is important to elucidate the underlying mechanisms linking green space and health. Objectives: This study aimed to evaluate machine learning models that can classify the type of vegetation (i.e., tree, low-lying vegetation, grass) from street view images; and to investigate the associations between street green space and socioeconomic (SES) factors, in Los Angeles County, California. Methods: SES variables were obtained from the CalEnviroScreen3.0 dataset. Microsoft Bing Maps images in conjunction with deep learning were used to measure total and types of street view green space, which were compared to normalized difference vegetation index (NDVI) as commonly-used satellite-based green space measure. Generalized linear mixed model was used to examine associations between green space and census tract SES, adjusting for population density and rural/urban status. Results: The accuracy of the deep learning model was high with 92.5% mean intersection over union. NDVI were moderately correlated with total street view-based green space and tree, and weakly correlated with low-lying vegetation and grass. Total and three types of green space showed significant negative associations with neighborhood SES. The percentage of total green space decreased by 2.62 [95% confidence interval (CI): −3.02, −2.21, p < 0.001] with each interquartile range increase in CalEnviroScreen3.0 score. Disadvantaged communities contained approximately 5% less average street green space than other communities. Conclusion: Street view imagery coupled with deep learning approach can accurately and efficiently measure eye-level street green space and distinguish vegetation types. In Los Angeles County, disadvantaged communities had substantively less street green space. Governments and urban planners need to consider the type and visibility of street green space from pedestrian's perspective.

Yb14MnSb11 is a magnetic Zintl compound as well as being one of the best high temperature p-type thermoelectric materials. According to the Zintl formalism, which defines intermetallic phases where cations and anions are valence satisfied, this structure type is nominally made up of 14 Yb2+, 1 MnSb49-, 1 Sb37-, and 4 Sb3- atoms. When Mn is replaced by Mg or Zn, the Zintl defined motifs become 13 Yb2+, 1 Yb3+, 1 (Mg, Zn)Sb410-, 1 Sb37-, and 4 Sb3-. The predicted existence of Yb3+ based on simple electron counting rules of the Zintl formalism calls the Yb valence of these compounds into question. X-ray absorption near-edge structure, magnetic susceptibility, and specific heat measurements on single crystals of the three analogs show signatures of intermediate valence Yb behavior and in particular, reveal the heavy fermion nature of Yb14MgSb11. In these isostructural compounds, Yb can exhibit a variety of electronic configurations from intermediate (M=Zn), mostly 2+ (M=Mn), to 3+ (M=Mg). In all cases, there is a small amount of intermediate valency at the lowest temperatures. The amount of intermediate valency is constant for M=Mn, Mg and temperature dependent for M=Zn. The evolution of the Yb valence correlated to the transport properties of these phases is highlighted. The presence of Yb in this structure type allows for fine tuning of the carrier concentration and thereby the possibility of optimized thermoelectric properties along with unique magnetic phenomena.

Electric resistivity, specific heat, magnetic susceptibility, and inelastic neutron scattering experiments were performed on a single crystal of the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2 in order to study the spin fluctuations near an antiferromagnetic (AF) quantum critical point (QCP). The resistivity and the specific heat coefficient for T ⩽ 1 K exhibit the power law behavior expected for a 3D itinerant AF QCP (ρ(T) ∼ T(3/2) and γ(T) ∼ γ0 - bT(1/2)). However, for 2 ⩽ T ⩽ 10 K, the susceptibility and specific heat vary as log T and the resistivity varies linearly with temperature. Furthermore, despite the fact that the resistivity and specific heat exhibit the non-Fermi liquid behavior expected at a QCP, the correlation length, correlation time, and staggered susceptibility of the spin fluctuations remain finite at low temperature. We suggest that these deviations from the divergent behavior expected for a QCP may result from alloy disorder.

OBJECTIVE - To establish minimal clinically important difference (MCID) scores representing the smallest detectable change in quality of life (QOL), using the Pediatric Quality of Life Inventory (PedsQL) Generic Core and Diabetes Module among youth with ia

OBJECTIVE - Youth with diabetes are at increased risk for depression. The objectives of this study were to provide preliminary evidence that this at-risk status for depression is associated with metabolic and inflammatory markers and to inform future, more

Measurements of both the average crystal structure from Rietveld refinement of neutron powder diffraction data and the local structure from La LIII-edge x-ray-absorption fine structure (XAFS) are presented for a La11B6 sample as a function of temperature (∼10-320 K). These data are compared to XAFS results on a EuB6 sample. The single-site La and B positional distribution widths and the La-B and La-La bond length distribution widths and their temperature dependence are compared. This comparison allows an estimate of the La and B site displacements, and we find that these sublattices are only slightly correlated with each other. Moreover, while the temperature dependence of the displacement parameters of the average sites obtained from diffraction fit an Einstein model well, the temperature dependence of the La-B bond length distribution width requires at least two vibrational frequencies, corresponding to the La and B frequencies of the individual sites. XAFS data on EuB6 indicate that the situation is the same in the Eu compound. In addition, comparisons between data taken below and above the ferromagnetic transition temperature for EuB6 place stringent limits on the lattice involvement in the associated metal-insulator transition and the ensuing large magnetoresistance effect. This lack of lattice involvement in the magnetoresistance transition is in sharp contrast to the strong lattice involvement observed in the colossal magnetoresistance lanthanum manganese perovskites.

We report a systematic study of the face-centered-cubic compounds Yb XCu4 (X=Ag, Au, Cd, Mg, Tl, and Zn), as well as their corresponding nonmagnetic analogues LuXCu4. X-ray diffraction, heat capacity, magnetic susceptibility, high-field magnetization, electrical resistivity, Hall effect, and LIII-edge absorption measurements have been performed. The compounds have Kondo temperatures that range from about 10 K to nearly 1000 K. Although the single-impurity Kondo model qualitatively describes the physical properties of these materials, the quantitative details are not well described and the quality of the fits varies strongly from compound to compound. Compound-to-compound variations in crystal-electric fields, effective valence, and the strength of f-ligand hybridization effects, as well as the influence of intrinsic disorder, may help to explain these discrepancies. © 1999 American Physical Society.

We report neutron-scattering experiments for (Formula presented) that were performed in the time-of-flight mode at a neutron spallation source. Two independent methods were used to determine the nonmagnetic scattering and both gave comparable results for the magnetic scattering. The magnetic scattering was measured at temperatures (Formula presented) and 60 K, below and above the temperature of the valence transition (Formula presented) Our key result is that the spin dynamics in the mixed valent phase are well described over a broad range of energy transfer (Formula presented) and incident energies (Formula presented) by a Lorentzian power spectrum, centered at (Formula presented) and with halfwidth (Formula presented) The magnetic susceptibility derived from the fits is within 20% of the value measured for the dc susceptibility. The peak energy is in good agreement with the Kondo temperature derived from thermodynamic studies but the Lorentzian line shape fits the data significantly better (Formula presented) than the line shape expected for a Kondo impurity (Formula presented) In addition we report results for (Formula presented) For this compound, the scattering is inelastic at low temperature (at 10 K (Formula presented) and (Formula presented)) but is quasielastic at higher temperature where (Formula presented) and 13.2 meV at 150 and 300 K, respectively. This increase in linewidth is contrary to the 50% decrease in linewidth predicted by the Anderson impurity model for this temperature range, and is also smaller than the factor of four increase in characteristic energy suggested by application of the impurity model to the magnetic susceptibility. © 1999 The American Physical Society.

We report a systematic study of the face-centered-cubic compounds Yb XCu4 (X=Ag, Au, Cd, Mg, Tl, and Zn), as well as their corresponding nonmagnetic analogues LuXCu4. X-ray diffraction, heat capacity, magnetic susceptibility, high-field magnetization, electrical resistivity, Hall effect, and LIII-edge absorption measurements have been performed. The compounds have Kondo temperatures that range from about 10 K to nearly 1000 K. Although the single-impurity Kondo model qualitatively describes the physical properties of these materials, the quantitative details are not well described and the quality of the fits varies strongly from compound to compound. Compound-to-compound variations in crystal-electric fields, effective valence, and the strength of f-ligand hybridization effects, as well as the influence of intrinsic disorder, may help to explain these discrepancies. © 1999 American Physical Society.

We report neutron-scattering experiments for (Formula presented) that were performed in the time-of-flight mode at a neutron spallation source. Two independent methods were used to determine the nonmagnetic scattering and both gave comparable results for the magnetic scattering. The magnetic scattering was measured at temperatures (Formula presented) and 60 K, below and above the temperature of the valence transition (Formula presented) Our key result is that the spin dynamics in the mixed valent phase are well described over a broad range of energy transfer (Formula presented) and incident energies (Formula presented) by a Lorentzian power spectrum, centered at (Formula presented) and with halfwidth (Formula presented) The magnetic susceptibility derived from the fits is within 20% of the value measured for the dc susceptibility. The peak energy is in good agreement with the Kondo temperature derived from thermodynamic studies but the Lorentzian line shape fits the data significantly better (Formula presented) than the line shape expected for a Kondo impurity (Formula presented) In addition we report results for (Formula presented) For this compound, the scattering is inelastic at low temperature (at 10 K (Formula presented) and (Formula presented)) but is quasielastic at higher temperature where (Formula presented) and 13.2 meV at 150 and 300 K, respectively. This increase in linewidth is contrary to the 50% decrease in linewidth predicted by the Anderson impurity model for this temperature range, and is also smaller than the factor of four increase in characteristic energy suggested by application of the impurity model to the magnetic susceptibility. © 1999 The American Physical Society.

An unrealistically large value of the Gruneisen parameter is required to explain the valence transition which occurs at 42 K in YbInCu4 as due to a Kondo Volume Collapse. A hint as to the origin of the transition lies in the large change in carrier density which occurs at the transition, from trivalent semimetallic behavior at high temperature to mixed valent metallic behavior at low temperature. In this paper we report measurements of the Hall coefficient RH for temperatures in the range 15-300 K for a series of RXCu4 compounds (R = Yb, Lu and X = Au, Zn, Cd, Mg, Tl) that form in the cubic C15b structure. For all X the Hall coefficients are small (∼10-10 m3/C) so that the transport appears to be metallic. The observation that low carrier density is unique to RInCu4 leads us to hypothesize that the valence transition (which is also unique to YbInCu4) is connected with the existence of a quasigap, which is a common feature of the band structure of RXCu4. The quasigap allows for two competing hybridization states of the 4f electrons: a small TK semimetallic state and a large TK metallic state. © 1998 Elsevier Science Ltd. All rights reserved.

We report measurements of the low-temperature specific-heat coefficient (Formula presented) cell volume (Formula presented) Hall coefficient (Formula presented) and valence (Formula presented) [where the Yb hole occupation (Formula presented) was determined from (Formula presented) x-ray absorption] of single crystals of (Formula presented) Alloying (Formula presented) with Ag increases the temperature (Formula presented) of the first-order isomorphic phase transition and causes it to terminate at a critical point at (Formula presented) and (Formula presented) The variation of (Formula presented) near the critical point is well described by a mean-field equation of state. The phase transition involves a large change in the Kondo temperature, and the transition temperatures (Formula presented) are of order of the Kondo temperatures (Formula presented) of the high-temperature state. The cell volume is found to vary proportionally to (Formula presented) At low temperatures, well away from the transition, the Wilson ratio of the susceptibility χ(0) and specific heat coefficient γ falls within 20% of the value predicted for a Kondo impurity, and (Formula presented) and χ(0) are roughly proportional as predicted from the Anderson model. The temperature dependence (Formula presented) for temperatures away from the phase transition also fits the predictions of the Kondo model. The small volume discontinuity (Formula presented) observed at (Formula presented) suggests that the phase transition is not due to a Kondo volume collapse. The large Hall coefficients (Formula presented) observed for (Formula presented) and (Formula presented) suggest instead that a low carrier density in the high-temperature state plays a key role in the phase transition. © 1997 The American Physical Society.

We have measured the momentum and energy dependence of the spin fluctuations in the low-temperature mixed-valent state and the high-temperature integral-valent state of (Formula presented), using flux-grown single crystals and a triple axis spectrometer. The magnetic scattering can be fit with a Lorentzian power spectrum, with positions and halfwidths equal (Formula presented)=2.3 meV and (Formula presented)=1.8 meV in the high-temperature state at 50 K and (Formula presented)=40.2 meV and (Formula presented)=12.3 meV in the low-temperature state at 20 K. Within the experimental uncertainties, the line shape as a function of energy transfer (i.e., the power spectrum) does not depend on momentum transfer Q. The static susceptibility χ(Q) is no more than 10% larger at the zone boundary than at zone center for the [1,0,0] direction. The results compare reasonably well to the predictions of the Anderson impurity model and to earlier measurements on polycrystalline samples. © 1997 The American Physical Society.

(Formula presented) undergoes a first-order isostructural valence transition near 40 K, whereas (Formula presented) is a moderately heavy (γ=250 mJ/mol (Formula presented)) mixed-valence compound. We have succeeded in growing single crystals of these compounds, as well as many intermediate alloys, using flux-growth techniques. The evolution from (Formula presented) to (Formula presented) has been characterized using electrical resistivity, magnetic susceptibility, and x-ray powder diffraction. The data are interpreted in terms of the evolution of the single-impurity Kondo temperature as a function of Ag concentration. © 1996 The American Physical Society.

We present neutron diffraction results for YbIn(Formula presented), and Rietveld refinements of the structure. The ground state has the same structure (C15B) as the high temperature state, so that the first-order phase transition at (Formula presented) K is indeed isomorphic, i.e., the lattice constant changes without a change of crystal symmetry. The site disorder and the diffraction linewidths decrease systematically on going from polycrystal samples with two transitions (at 40 and 70 K) to polycrystals with a single (40 K) transition to flux-grown single crystals with a sharp transition at 40 K. We argue that in site-disordered samples, the effect of doping Yb onto the In site is to increase (Formula presented) and cause the transition to become continuous. © 1996 The American Physical Society.

The results of an on-going study of YbIn1-xAgxCu4 are presented. YbInCu4 undergoes a first-order valence transition at 40 K, while YbAgCu4 is an isostructural heavy Fermion compound. We have succeeded in growing single crystals of these compounds, as well as intermediate alloys, using flux-growth techniques. A smooth evolution from YbInCu4 to YbAgCu4 is observed. Results on the influence of sample quality, as well as the effect of other dopants, on the valence transition in YbInCu4 are also discussed.

The results of an on-going study of YbIn1-xAgxCu4 are presented. YbInCu4 undergoes a first-order valence transition at 40 K, while YbAgCu4 is an isostructural heavy Fermion compound. We have succeeded in growing single crystals of these compounds, as well as intermediate alloys, using flux-growth techniques. A smooth evolution from YbInCu4 to YbAgCu4 is observed. Results on the influence of sample quality, as well as the effect of other dopants, on the valence transition in YbInCu4 are also discussed.

We present results for the resistivity, the magnetoresistance, and the specific heat of (Formula presented)(Formula presented)(Formula presented) and (Formula presented). The impurity contributions to these measurements follow the predictions of the single-impurity Kondo model for a Kondo temperature (Formula presented)≊65 K, assuming that the impurity behaves as a crystal-field split ((Formula presented)) doublet. Assuming a J=5/2 impurity, the value of (Formula presented) needed to fit these experiments varies from 65 to 125 K. The contribution to the susceptibility may be too small to be explained by the model. These results address whether the nonmagnetic impurity behaves as a Kondo hole. © 1996 The American Physical Society.

We report the behavior of the hexagonal compound CePtPb, which has an antiferromagnetic transition at (Formula presented) K. The magnetic susceptibility is highly anisotropic, with the ratio (Formula presented) extrapolating to the value 65 at (Formula presented). The low-temperature magnetization is also anisotropic with (Formula presented) saturating to (Formula presented) atom at (Formula presented) T, where (Formula presented) is five times smaller. The anisotropy is due both to low-symmetry crystal fields and to exchange anisotropy, which causes basal plane ferromagnetic fluctuations to develop below (Formula presented) K. Three facts suggest that the magnetic order might coexist with heavy-fermion behavior: heat-capacity data show a linear-in-temperature contribution (Formula presented) mJ/mol (Formula presented) in the antiferromagnetic state; the resistivity is quadratic in temperature below (Formula presented); and the magnetic entropy is generated very slowly with temperature reaching a value of only (Formula presented) at (Formula presented). On the other hand, the long high-temperature tail of the heat-capacity data correlates with the ferromagnetic fluctuations above (Formula presented); and ac susceptibility measurements under hydrostatic pressure (to 17 kbar) show that (Formula presented) increases with pressure at an approximate rate 20 mK/kbar, which suggests that CePtPb sits in the small (Formula presented) limit of the Doniach phase diagram; hence heavy-fermion effects may be negligible. © 1996 The American Physical Society.

We report measurements of the resistivity ρ, Sommerfeld coefficient of specific heat γ, and magnetization M of polycrystalline YbAgCu4 in high magnetic fields 0≤B≤18 T [in the case of M(B) to 50 T]. A comparison of the temperature-dependent susceptibility χ(T) as well as field-dependent Sommerfeld coefficient γ and magnetization to Kondo theory for a J=7/2 impurity shows that theory correctly predicts the functional dependence of these quantities on T and B, but the characteristic temperatures determined from the various measurements (120, 98, 77, and 63 K) differ by nearly a factor of 2, which is difficult to understand within the context of Kondo theory even when other possible contributions are considered. In addition the normalized (Wilson) ratio of χ to γ is 1.00 at zero field (compared to 1.14 in Coqblin-Schrieffer theory) and decreases with increasing magnetic field. The magnetoresistance is positive at all temperatures, reaching a value Δρ(B)/ρ(B=0)=0.6 at 25 mK and 18 T. The low-temperature magnetoresistivity Δρ(B) varies as B1.5. We argue that this is dominated by an ordinary impurity effect. Kohler's rule is clearly violated as the temperature is raised; the scattering rate appears to increase with field below 40 K and decrease with field above 40 K. This behavior is expected for an Anderson lattice when a pseudogap is present. At low temperature the resistivity increases as AT2. The coefficient A (corrected for cyclotron-orbit effects) increases with field such that the ratio A(B)/γ(B)2 is a constant. Doping with Lu onto the Yb site, or with Ni onto the Cu site, changes the magnitude of the low-temperature resistivity in a manner consistent with the predictions of the theory of ligand-induced disorder in an Anderson lattice. © 1995 The American Physical Society.

We report evidence of 4f band character in Ce 4f states at T ≫ TK using high-resolution angle-resolved resonant photoemission. The Ce intermetallic compound CePt2+x was grown and studied in situ by the method of MBE and was characterized by LEED, XPS and XAS. These new findings suggest a need for a re-examination of 4f photoemission in Ce compounds. © 1995.

The electrical resistivity (ρ{variant}) and magnetoresistance of polycrystalline YbAgCu4 have been measured at temperatures between 25 mK and 300 K, and at magnetic fields (B) up to 18 T. The magnetoresistance (ρ{variant}(B) - ρ{variant}(0))/ρ{variant}(0)) is positive at all temperatures below 200 K and reaches its maximum of 60% at 18 T and 25 mK. The field- and temperature-dependent resistivity does not scale in a simple way. The opposite sign of the magnetoresistance at ambient and high pressure can be explained qualitatively by crystal-field effects lifting the degeneracy of the J = 7 2 groundstate. The linear coefficient of the specific heat (γ) measured at fields up to 10 T shows a quadratic field dependence. We did not find a linear relation between γ2 and A, the T2-coefficient of the temperature-dependent resistivity, with the applied magnetic field as the implicit parameter. © 1995.

We report evidence of 4f band character in Ce 4f states at T ≫ TK using high-resolution angle-resolved resonant photoemission. The Ce intermetallic compound CePt2+x was grown and studied in situ by the method of MBE and was characterized by LEED, XPS and XAS. These new findings suggest a need for a re-examination of 4f photoemission in Ce compounds. © 1995.

Ambient pressure characteristics of heavy-fermion compounds, such as the ratio of the low temperature magnetic susceptibility to the electronic specific heat coefficient γ and a simple relationship between the T2-coefficient of resistivity and γ2, suggest that a single-energy scale T0 dictates the physics of these materials. Such is the case for Kondo-impurity systems to which heavy-fermions are related. We consider the consequences of assuming that the electronic free energy is given by a universal function of T/T0(V) where V is the molar volume. We show that volume-dependent magnetic susceptibility, specific heat and electrical resistivity of some heavy-fermion compounds scale as T/T0(V), at least over a range in pressures and temperatures. A further consequence of the principle assumption is that Gruneisen parameters defined as ∂ln X/∂ln V, where X is some physical property, should be identical for all properties and equal to that determined from electronic contributions to the volume-thermal expansion coefficient and specific heat. In several materials, this equality holds, at least approximately. Although evidence is found for single-energy scaling in heavy-fermion materials, we cannot conclude unambiguously that the basic assumption is correct in detail. © 1994 Plenum Publishing Corporation.

A high-resolution photoemission (PES) study of the heavy-fermion compound YbAl3 has been undertaken to test the qualitative and quantitative predictions of the single-impurity model. Corroborating data on YbAgCu4 and YbCu2Si2 are also presented. For Yb-based heavy fermions the model predicts a fully occupied Kondo resonance so that its width, intensity, and temperature dependence should be directly accessible by PES. Due to the existence of temperature- and/or contamination-dependent surface features, which are not dealt with by the model, a rigorous normalization and curve-fitting procedure was required to extract the bulk 4f line shape. For the particular temperature cycling method employed by us, we do not observe any temperature dependence in the peak that had been previously identified as the Kondo resonance. We find that both the binding energy and width of this peak are significantly larger than theory predicts. It is also found that the trends in 4f line shape and surface shift between YbAl3 and LuAl3 are consistent with the trends seen between the 4f core levels of elemental Yb and Lu. Similar results are also found in YbCu2Si2 and YbAgCu4 for similar cycling methods. Recent observations of temperature dependence in these systems are most easily understood in terms of surface phenomena. © 1993 The American Physical Society.

We present valence-band photoemission spectra for CeAl3, CeBe13, CeSi2, CeCu2Si2, and related conventional rare-earth counterpart compounds, taken at photon energies corresponding to the giant 4d resonance with resolution ∼150 meV. We take into account the 5d emission, which comprises 30% of the valence-band emission at the 4d resonance. We compare the resulting 4f emission to the predictions of the Anderson impurity model calculated in a low-order 1/N expansion, and including spin-orbit, crystal-field, and finite Coulomb correlation effects. The calculation gives order-of-magnitude fits to the data, but underestimates the spectral weight near the Fermi level by a factor of 2 and overestimates the width of the main f emission at 2 eV by a factor of 4. We argue that Ce photoemission remains an open problem and discuss several experimental and theoretical issues which need to be resolved to make further progress. © 1993 The American Physical Society.

Resonant photoelectron spectroscopy has been used to examine the electronic structure of Ce- and Yb-based heavy fermions. The experimental results are compared with Gunnarsson-Schönhammer calculations which include crystal field and finite Uff effects. Comparison of the model and experimental results reveals a large disparity between predictions and actual results. In particular, the Kondo model predictions of width, energy position and spectral weight for features near the Fermi level are not realized. Additionally, there is disparity between calculation and photoemission data in the Fermi-level crossing positions for spectral features very near the Fermi level. These discrepancies are present for both Ce and Yb heavy fermion systems. We see no evidence of spectral features in the photoemission data which can be uniquely identified with the Kondo resonance while our calculations show the resolution is adequate to clearly distinguish such features. © 1993.

Ce3Bi4Pt3 is a cerium compound that exhibits a hybridization gap and concomitant semiconducting behavior in the coherent ground state. Using neutron powder diffraction, we have determined the variation of the lattice constant with temperature at two pressures (P=10-3 and 17.7 kbar), and determined the bulk modulus and atomic mean-square displacements for Ce3Bi4Pt3 and its normal analog, La3Bi4Pt3. The thermal expansion Δβ in Ce3Bi4Pt3 exhibits a maximum at Tmax=50 K at ambient pressure. Below 50 K, the bulk modulus ΔB is proportional to TΔβ. We apply a Grüneisen analysis, under the assumption that the free energy exhibits T/T0(V) scaling. The Grüneisen parameter deduced from the ratio ΔB/TΔβ is consistent with the value Ω=36 deduced from the pressure variation of Tmax. The analysis allows us to predict the temperature dependence of the 4f specific heat (ΔCΔβ/Ω), which thus has a maximum at 50 K and a high-temperature entropy nearly equal the expected value R ln6. We argue that the maximum at 50 K reflects an (indirect) hybridization gap of order 100 K. We show further that the lattice constant anomaly Δa0 is proportional to the effective moment Tχ; this suggests that a relationship known to be valid for antiferromagnets, namely (Tχ)/TΔC where ΔC is the specific heat, may be valid for Ce3Bi4Pt3. Finally, we show that the temperature dependence of the mean-square atomic displacements is nearly identical for Ce3Bi4Pt3 and La3Bi4Pt3 and can be fitted by a simple Debye-Waller model; hence the expansion anomaly does not affect the average lattice dynamics. © 1992 The American Physical Society.

We report high-resolution photoemission results for the 4f levels in YbCu2Si2 and CeSi2. The data are compared to the predictions of the Anderson impurity model for valence band photoemission. These predicted spectra are obtained both in an approximate fashion by broadening crystal field (CF) states whose parameters are determined from existing neutron scattering data, as well as from a Gunnarson-Schonhammer calculation. Inclusion of crystal fields does not affect our two fundamental conclusions: that there is a natural linewidth in the problem (≈130meV) which is much greater than predicted by the Anderson model, and that the expected temperature dependence of the Kondo resonance is absent. Due to the large natural linewidth, experimental resolution (60-95meV) is not a limiting factor. © 1992.

We report valence band photoemission results for YbCu2Si2, The 4f13(J = 7 2) final state peak, centered 60 meV below the Fermi level ε{lunate}F, lacks the temperature dependence and is broader than predicted for a Kondo resonance. Together with recent photoemission results for cerium compounds, these results raise serious doubts about the Kondo impurity explanation of heavy fermion photoemission. © 1992.

We report resistivity, magnetic, thermodynamic, and neutron-diffraction data for the heavy-fermion compound Ce5Sn3. These data indicate an antiferromagnetic phase transition at TN=17.5 K, but at lower temperatures the linear coefficient of specific heat (T)=C(T)/T rises to 1.6 J/f.u. mol K2, characteristic of a moderately-heavy-fermion compound. Only a small amount of entropy is liberated by the phase transition (R ln2), whereas most of the entropy [(34)R ln2] is liberated by heavy-fermion processes. This implies a small ordered moment. Further, neutron diffraction implies a rather complicated magnetic order. We discuss two alternatives: (a) that ordering occurs on the Ce site of higher symmetry, while heavy-fermion behavior occurs on the lower-symmetry Ce site; and (b) that itinerant-fermion antiferromagnetism occurs. Due to the overall low site symmetries, crystal-field effects are strong; in particular, the susceptibility is highly anisotropic (by a factor of at least 20 at low temperatures) and enhanced by the presence of strong ferromagnetic correlations in the heavy-fermion state. © 1991 The American Physical Society.

We present the results of electronic transport, magnetic susceptibility, and thermodynamic measurements on single crystals of the cubic compound Ce3Bi4Pt3. The susceptibility displays a broak peak centered at Tmax = 80K, which in Ce compounds is usually indicative of mixed valence and moderately heavy-electron behavior. Both the electronic transport properties and the low-temperature specific heat indicate that Ce3Bi4Pt4 is nonmetallic with a transport energy gap of roughly 35 K. We argue that this temperature is close to that scale over which coherence should develop in a periodic metallic system with Tmax = 80K. Resistivities typical of a Kondo-impurity system are realized when the compound is alloyed with moderate amounts of lanthanum. Further, lanthanum substitution increases the low-temperature specific heat to a value consistent with the single-ion energy scale determined from the magnetic susceptibility. © 1991.

We present resistivity (T), susceptibility (T), and specific heat C(T) data for Ce3Bi4Pt3. The susceptibility exhibits a broad maximum centered near 80 K, typical of a somewhat-heavy-electron compound; were the material metallic, a linear coefficient of specific heat =75 mJ/mol Ce K2 would be expected. However, the compound is InotR metallic, as indicated by its resistivity which rises to large values at low temperatures and exhibits activated behavior with an activation energy /kB=35 K. By analogy to SmB6 and YbB12, this energy gap arises from 4f-electron conduction-electron hybridization. Due to the gap, electronic excitations are suppressed at low temperatures and the specific heat is smaller than in nonmagnetic La3Bi4Pt3. Alloying with lanthanum ((Ce1-xLax)3Bi4Pt3) decreases the resistivity and increases the specific heat towards the value expected for the metallic case; i.e., for moderate alloying (x=0.07) the behavior is that of a moderately disordered heavy-electron metal. We argue that lattice periodicity is an essential requirement for the formation of the hybridization gap. © 1990 The American Physical Society.

The compounds Ce3Sn, Ce3In and Ce3Al are characterized by a small energy scale that is reflected in the magnetic susceptibility and temperature dependent electrical resistance. We have investigated the effect of hydrostatic pressure on their electrical resistance and find a response that is typical of Kondo lattice behavior. In addition, both Ce3In and Ce3Al undergo a phase transition induced by pressure which, in the case of Ce3Al, is reminiscent of the γ-α transition in cerium. © 1987.

The pressure-temperature phase diagram of Ce0.9-xLaxTh0.10 alloys is presented for 0.1≤x≤0.17. Two critical points are found in this range of compositions. The data are shown to be consistent with an analysis based on the known Fermi-liquid behavior of Ce in compounds and alloys. The possible appearance of β phase at intermediate pressures is noted.

We report the results of resistivity measurements on Ce0.9-xLaxTh0.1 alloys for x=0.10,0.11,0.14, and 0.17 in the temperature interval 4.2-300 K and for the pressure range 0-12 kbar. Using these results we have semiquantitatively determined the P-T phase boundary for the isomorphic - phase transition for each concentration x. For x=0.10,0.11, and 0.14 the transitions are continuous at zero pressure, first order for pressures within the interval PcL(x)Pcu(x). Hence, for these concentrations the phase boundaries terminate at two critical points. For x=0.17, all observed transitions are continuous. Hence, in x-P-T space the surface of first-order transitions terminates at a critical edge (Tc(x),Pc(x)) such that, over an interval of x,Pc(x) is double valued and such that there is a "critical inflection point." These unusual features can be understood qualitatively as following from very general Fermi-liquid properties of the cerium 4f electronic system, together with the dilution and negative-pressure effects of alloying with lanthanum. We show that this qualitative description is consistent with existing experimental data. © 1984 The American Physical Society.

The low temperature resistivity of Ce0.9-xLaxTh 0.1 alloys is known to vary as ρ0+αT 2. We have investigated the variation of ρ0 and α with pressure for several concentrations x. An unusually strong nonlinear decrease of the residual resistivity with pressure occurs; the magnitude of the decrease is an order-of-magnitude larger than in the isostructural nonmagnetic alloy La0.8Th0.2. The temperature coefficient α(P) also decreases strongly. These results are in qualitative accord with recent theories of the resistivity of disordered valence fluctuation compounds.

It is shown that the P-T diagram for the phase transition in Ce0.8La0.1Th0.1 has two critical points with first-order transitions between them. This phase diagram follows from the Fermi-liquid properties of the 4f electronic system, the experimentally known volume dependence of kBTFL, and the dilution effect of alloying. © 1983 The American Physical Society.

It is shown that the P-T diagram for the phase transition in Ce0.8La0.1Th0.1 has two critical points with first-order transitions between them. This phase diagram follows from the Fermi-liquid properties of the 4f electronic system, the experimentally known volume dependence of kBTFL, and the dilution effect of alloying. © 1983 The American Physical Society.

We report the results of resistivity measurements on Ce0.9-xLaxTh0.1 alloys for x=0.10,0.11,0.14, and 0.17 in the temperature interval 4.2-300 K and for the pressure range 0-12 kbar. Using these results we have semiquantitatively determined the P-T phase boundary for the isomorphic - phase transition for each concentration x. For x=0.10,0.11, and 0.14 the transitions are continuous at zero pressure, first order for pressures within the interval PcL(x)Pcu(x). Hence, for these concentrations the phase boundaries terminate at two critical points. For x=0.17, all observed transitions are continuous. Hence, in x-P-T space the surface of first-order transitions terminates at a critical edge (Tc(x),Pc(x)) such that, over an interval of x,Pc(x) is double valued and such that there is a "critical inflection point." These unusual features can be understood qualitatively as following from very general Fermi-liquid properties of the cerium 4f electronic system, together with the dilution and negative-pressure effects of alloying with lanthanum. We show that this qualitative description is consistent with existing experimental data. © 1984 The American Physical Society.

Background: Youth with type 1 diabetes (T1D) are encouraged to participate in physical activity (PA). Studies have identified fear of hypoglycemia (FOH) as a barrier to participating in PA. Objectives: To examine (a) PA patterns in youth with T1D by age group and (b) the relationship between both parental and youth FOH and youth PA. Methods: A cross‐sectional analysis from the SEARCH cohort study visit of youth ages 10 to 17 years with T1D (n = 1129) was conducted. Linear regression models estimated the association between self‐reported number of days of vigorous PA (VPA) and moderate PA (MPA) and both youth‐ and parent‐reported FOH. Multivariable models were adjusted for age, sex, race, duration of T1D, HbA1c, use of continuous glucose monitoring (CGM), recent severe hypoglycemia, primary insulin regimen, and BMI. Results: Participants were 52% female, had mean (sd) age 14.4 (4.2) years, diabetes duration 7.5 years (1.8), HbA1c 9.2% (1.7). Older youth were less likely to engage in VPA (P <.01), or sports teams (P <.01), but more likely to engage in MPA (P <.01). Higher youth FOH (behavior subscale) was associated with increased levels of VPA (β (se) 0.30 (0.11), P =.01) but not significantly associated with MPA (P =.06). There was no statistically significant association between parental FOH and youth PA. Conclusions: In SEARCH participants with T1D, VPA, and team sports participation declined with age, while MPA increased. We observed that higher scores on the youth FOH behavioral subscale were associated with increased VPA levels, suggesting that FOH may be less of a barrier to PA than previously thought. [ABSTRACT FROM AUTHOR]