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Effects of the Co substitution for Fe on the strongly anisotropic ferrimagnet HoFe 5 Al 7 are studied on single-crystalline samples with a tetragonal crystal structure of the ThMn 12 -type. For HoFe 5- x Co x Al 7 , we found the homogeneity range up to x = 2.5. The Co substitution results in a shrinkage of the tetragonal lattice within the basal plane, whereas the c parameter does not change. The exchange interactions and magnetic anisotropy are strongly affected by the Co substitution. The detrimental effect of Co on the Curie temperature T C in HoFe 5- x Co x Al 7 compounds is very unusual. The Curie temperature linearly falls from 216 K for x = 0–67 K for x = 2.5, which is unexpected because the Co substitution for Fe in 3d-4f intermetallic compounds usually increases the magnetic ordering temperatures due to the strengthening of exchange interactions. At the same time, the compensation temperature changes very little between 65 K and 72 K. At 2 K, spontaneous magnetic moment increases from 2 μ B at x = 0–4.2 μ B at x = 2.5. Magnetization measurements have been performed in pulsed magnetic fields up to 58 T. The compounds exhibit a high magnetic anisotropy of the easy-plane type with the [110] axis as the easy-magnetization direction. Along the easy axis, two first-order field-induced magnetic transitions (at 17 T and 37 T) are observed for HoFe 5 Al 7 and one transition at 27 T for HoFe 4 CoAl 7 . The magnetization curve has an S-shape for HoFe 3 Co 2 Al 7 . [ABSTRACT FROM AUTHOR]

Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn 2 type, space group P 6 3 /mmc , with lattice parameters a =536.4 pm, c =845.3 pm. Shortest inter-uranium distance 313 pm (along the c- axis) is considerably smaller than the Hill limit (340 pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10 −8 m 3 mol −1 (at T =2 K), which is slightly higher with magnetic field along the a- axis compared to the c- axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ =36 mJ mol −1 K −2 . [ABSTRACT FROM AUTHOR]

Studies by means of neutron diffraction and inelastic neutron scattering, the properties of terbium, nickel and aluminium (TbNiAl) hydrides and deuerides. What the magnetic order in intermetallic TbNiAl is based on; Examination of the localized vibrations of hydrogen in TBNiAIH1.39 using inelastic neutron scattering; Results of the study.

Abstract: LuFe x Al12− x (4⩽ x ⩽6) single crystals with the tetragonal structure of the ThMn12-type have been studied in magnetic fields up to 14T. In this composition range the magnetic exchange interactions are very sensitive to the Fe content. LuFe4Al8 and LuFe4.5Al7.5 are antiferromagnets with the Néel temperature around T N =120K. Antiferromagnetic exchange interactions weaken with increasing Fe content. LuFe4.5Al7.5 and LuFe5Al7 display a metamagnetic transition to a non-collinear ferromagnetic state. The transition is not observed in LuFe5.5Al6.5 that displays only some traces of antiferromagnetic exchange interactions at low temperatures. In the LuFe x Al12− x compounds with 5⩽ x ⩽5.5 antiferromagnetism becomes suppressed at a rather low temperature, above which ferromagnetic exchange interactions dominate. The temperature interval where they are dominant broadens with increasing x as T N decreases and the Curie temperature T C increases. Antiferromagnetism is absent in LuFe6Al6 that displays normal ferromagnetic behavior with T C =327K. [Copyright &y& Elsevier]

Substitution of Y for U in the itinerant 5f-electron metamagnet, UCoAl, transforms the system to a ferromagnetic state. Application of external hydrostatic pressure above 0.3 GPa suppresses the spontaneous ferromagnetism and restores the paramagnetism with field-induced transition to ferromagnetic state. However, the transition becomes of the second order instead of the first-order one in parent UCoAl. [ABSTRACT FROM AUTHOR]

UCo2Si2 orders antiferromagnetically at TN=82.5 K. The magnetic ordering is accompanied by pronounced anomalies of the specific heat, magnetization and resistivity. Resistivity is notably anisotropic depending on the current direction. We have observed the evolution of the TN-related resistivity features with increasing hydrostatic pressure up to 7.3 GPa. TN value decreases with increasing pressure; the critical pressure for the collapse of the ordered magnetism is about 8 GPa. [ABSTRACT FROM AUTHOR]

Abstract: Effect of dilution of the U sublattice by non-magnetic Lu on the magnetic anisotropy and magnetostriction of UFe2 has been studied on single crystals of U0.8Lu0.2Fe2. The observed change of the anisotropy-type from the 〈111〉 easy-magnetization axis in UFe2 to the 〈100〉 axis in U0.8Lu0.2Fe2 is accompanied by disappearance of the spontaneous magnetostrictive distortion in U0.8Lu0.2Fe2 due to small magnetostriction constant λ 100 =0.26×10−3 (at 4.2K). Nevertheless, the magnetostriction measurements revealed that U0.80Lu0.20Fe2 has large λ 111 =1.2×10−3 which belongs to a “giant magnetostriction” range. [Copyright &y& Elsevier]

The magnetization study was performed on single crystals of uranium intermetallic compounds R2T13.6Si3.4 (R=U, Lu; T=Fe, Co). A very different behavior of the U sublattice was observed for T=Fe and Co. In U2Fe13.6Si3.4, the U sublattice is magnetic and contributes a lot to the exchange and anisotropy energies whereas in U2Co13.6Si3.4 it is presumably non-magnetic. Influence of U in the latter case consists in reduction of the Co magnetic moments and exchange interaction between them, which causes a much lower molecular magnetic moment and Curie temperature in U2Co13.6Si3.4 compared to Lu2Co13.6Si3.4. [Copyright &y& Elsevier]

Si solubility extends up to x=3.4 in the Lu2Fe17-xSix solid solutions. The Si atoms substitute the Fe ones on the 6g and 12k positions, the other Fe sites are Si-free, the lattice parameters of hexagonal crystal structure decrease with increasing Si content. The anti-ferromagnetism in Lu2Fe17 at elevated temperatures is suppressed, all the solid solutions are ferromagnetic and the Curie temperature increases up to 470 K at the solubility limit. The easy-plane type of magnetic anisotropy is preserved for all the solid solutions. The Fe magnetic moment and the magnetic anisotropy energy decrease with Si substitution. [Copyright &y& Elsevier]

DyNiAl orders ferromagnetically below TC=30 K with the Dy magnetic moments oriented along the hexagonal c-axis, and undergoes an order–order magnetic phase transition at T1=15 K where an antiferromagnetic component appears in the basal plane leading to a non-collinear magnetic structure. Magnetization measurements on a DyNiAl single crystal in fields up to 40 T revealed a large uniaxial magnetic anisotropy with anisotropy field of 25 T and field-induced transitions in fields applied along the basal plane. A low-field transition is observed in both magnetic phases and is associated with a rotation of the total magnetic moment toward the field direction to form a canted magnetic structure, which is stable in a wide field interval. A high-field transition is observed only in the low-temperature phase and corresponds to a spin flop of the antiferromagnetic component. [Copyright &y& Elsevier]

The uranium contribution to the magnetism of U–Fe–Si compounds with hexagonal crystal structure of the Th2Ni17 type has been investigated by means of a magnetization study of single crystals that have been grown for the first time. The U contribution to the total magnetic moment is almost negligible. Nevertheless, U strongly influences the magnetic properties, which points to considerable spin and orbital components of the U magnetic moment. A considerable U spin moment is clear from the enhanced Curie temperature of U2Fe13.6Si3.4 (530 K) compared to that of Lu2Fe13.6Si3.4 (470 K). Evidence for a considerable U orbital moment is the strongly enhanced magnetic anisotropy of U2Fe13.6Si3.4 compared to that of Lu2Fe13.6Si3.4. Both the Fe and the U sublattices provide basal-plane type of magnetic anisotropy. The Fe sublattice is characterized by the first anisotropy constant K1=−0.84 MJ/m3 at 4.2 K. The U sublattice exhibits nearly the same contribution to K1 and gives rise to a large negative K2, which is manifested by the strong non-linearity of the magnetization curve and the FOMP-like transition at the critical field μ0Hc=3.3 T. Also, in-plane anisotropy, absent in the Lu compounds, is observed in U2Fe13.6Si3.4 with the easy magnetization axis 〈1 2 0〉 (the b-axis in the orthorhombic notation). All these specific features are associated with U atoms on the 2b positions. [Copyright &y& Elsevier]

UCoAl has a paramagnetic ground state. Nevertheless, it exhibits a susceptibility maximum at Tmax≈20 K and a metamagnetic transition at lower temperatures that is induced by a magnetic field applied along the c-axis of the hexagonal ZrNiAl-type of structure. We have performed the first-principles electronic-structure calculations for this material in the framework of the density functional theory (DFT) and confirmed the close proximity of the threshold between the paramagnetic and the ferromagnetic state. Some aspects of the calculated charge-density distribution (e.g. the equilibrium volume and the electric-field gradient) are in good agreement with experiment but in contrast to earlier DFT studies it was found that the stable DFT ground state is ferromagnetic. The specific magnetic behavior is easily modified to ferromagnetism or conventional paramagnetism by doping UCoAl with suitable elements. To demonstrate these features we measured the magnetization as a function of magnetic field and temperature on single crystals of UCo1−xTxAl (T=Fe,Ni) solid solutions. In the course of this study, we investigated also the compounds UCo0.90Fe0.05Ni0.05Al and UFe0.50Ni0.50Al that are isoelectronic with UCoAl. All the studied compounds are isostructural with UCoAl and exhibit a strong uniaxial anisotropy with the dominating magnetic response along the c-axis. Ni substitution for Co leads to an increase of the critical field and to a gradual suppression of the metamagnetic transition, which disappears at x=0.10. On the other hand, Fe doping yields ferromagnetism. The compounds UCo0.90Fe0.05Ni0.05Al and UFe0.50Ni0.50Al also order ferromagnetically, below 30 and 52 K, respectively. [Copyright &y& Elsevier]

Lu2Fe17 is a ferromagnet below TC=140 K and antiferromagnet up to TN≈ 278 K. Hydrogen absorption leads to a stabilization in the ferromagnetism over the whole range of magnetic order and to an increase of the ordering temperature up to TC=354 K in Lu2Fe17H1. The external pressure compensates the lattice expansion upon hydrogenation, and a re-entrance of antiferromagnetism is observed. [ABSTRACT FROM AUTHOR]

Abstract: CeCoGe is an antiferromagnet with the Ce magnetic moments lying in the basal plane of the tetragonal lattice. A metamagnetic transition with a magnetization jump of 0.5 μ B is observed at B c=8.5T (at 2K) applied along the a-axis. With increasing temperature, the B c value passes through a minimum in the vicinity of T N and then increases up to at least 10K, i.e. above T N=5.5K. In a field along the c-axis, a broad S-shape magnetization curve is observed only at temperatures below T N. The anisotropic behavior persists above T N as well. [Copyright &y& Elsevier]

Abstract: The thermal expansion of Lu2Fe17− x Si x solid solutions has been measured by X-ray powder diffraction. The magnetic ordering in all compounds within the homogeneity range (x⩽3.4) is accompanied by a large spontaneous volume magnetostriction, distributed anisotropically over the principal axes of the hexagonal crystal structure. The volume effect ω s in the ground state reaches 14.7×10−3 in Lu2Fe17 and decreases monotonously to 8.9×10−3 for x=3.4, following the reduction of magnetic moment. Despite a still large ω s, the Invar behavior observed in Lu2Fe17 changes to a positive thermal expansion for x>1 due to an increasing Curie temperature. [Copyright &y& Elsevier]

Abstract: We present study of the anisotropic magnetocaloric effect in DyNiAl. This compound crystallizes in the hexagonal ZrNiAl-type structure, orders magnetically below and undergoes a further magnetic phase transition at . The Dy-moments are aligned ferromagnetically along the hexagonal -axis below , the additional antiferromagnetic component develops within the basal plane below . The magnetocaloric effect was evaluated from the magnetization measurements with field applied along the -axis and perpendicular to it. Our data reveal a strong anisotropy of the magnetocaloric effect. The large effect occurs for field applied along the -axis whereas the entropy change is small for the perpendicular field direction. [Copyright &y& Elsevier]

Abstract We present the results of ac and dc magnetic susceptibility and isothermal magnetization measurements (T = 2–300 K) on the single crystals of a metallic kagome lattice, Tb 3 Ru 4 Al 12 , reported recently to undergo reentrant magnetism with the onset of long range antiferromagnetic order below (T N =) 22 K. The magnetization data obtained on the crystal with the c -axis orientation along magnetic-field reveal spin-glass-like characteristics near 17 K (below T N). However, for the orientation along basal plane, such glassy anomalies are not observable above 2 K. In this respect, this compound behaves like an 'anisotropic' re-entrant spin-glass. Possible implications of this finding to the field of 'geometrically frustrated magnetism' are considered. Highlights • Tb 3 Ru 4 Al 12 , is one of the rare intermetallics with kagome lattice features. • This compound exhibits Néel order at 22 K. • Spin-glass features are seen below about 17 K along c-direction only. • Anisotropic spin-glass feature is possibly due to geometrical frustration. [ABSTRACT FROM AUTHOR]

Highlights: [•] Structure and magnetic states of alloys R2Fe14B (R=Nd, Er) before and after irradiation by fast neutrons with fluence up to 1.2×1020 neutrons per cm2 are studied. [•] The irradiation leads to amorphization of both alloys. [•] The Curie temperature considerably decreases and the coercivity vanishes upon irradiation of the samples. [•] Antiparallel orientation of the Fe and Er magnetic moments remains after amorphization in Er2Fe14B. [ABSTRACT FROM AUTHOR]

Abstract: Studies of magnetic and magneto-acoustic characteristics of the intermetallic compound UCu0.95Ge with antiferromagnetic ground state have been performed on single crystals in pulsed magnetic fields up to 64T applied along the main axes. Along the a axis, a first-order phase transition has been observed at 61T. For the field applied along the c axis, the first-order phase transition occurs at a much lower magnetic field (38T). In both directions, the magnetization trends to saturate at 1.35μB per formula unit. These field-induced transitions as well as the spontaneous transition at the magnetic ordering at T N =48K are accompanied by pronounced anomalies in the sound velocity and sound attenuation. The field-temperature phase diagrams are constructed for both directions of the magnetic field. The results of our theoretical analysis within the framework of the mean-field approximation qualitatively agree with the observed behavior of magnetic and magneto-acoustic characteristics of UCu0.95Ge. [Copyright &y& Elsevier]

Abstract: U-based intermetallic compound UNiGe absorbs hydrogen up to the stoichiometry UNiGeH1.2. In analogy to other compounds with the TiNiSi-type of structure, the structure is modified into hexagonal. The zig-zag U-chains are stretched, the U–U spacing is largely enhanced and the ordering temperature increases up to 100K. The ordered state has a spontaneous moment, but it is unlikely to be a simple ferromagnet. [Copyright &y& Elsevier]

Abstract: Compounds R2−x Fe14+2x Si3 with (R=Ce, Nd, Gd, Dy, Ho, Er, Lu, Y) were prepared by the modified Czochralski method and investigated by means of the 57Fe 14.4keV Mössbauer spectroscopy and powder X-ray diffraction. The magnetic moment was additionally measured for samples being single crystals. Iron experiencing low magnetic hyperfine field and electric quadrupole interaction was found on (4e) sites in the P63/mmc structure. Similar iron was found in the structure as well. The non-stoichiometry parameter was determined as being close to 2x =0.5 for all compounds investigated. Compound with R=Ho crystallizes in both structures. Our results show that silicon avoids (4f) and (6g) sites for compounds with the P63/mmc structure (R=Dy, Ho, Er, Lu, Y), whereas it avoids (6c) and (9d) sites for those with structure (R=Nd, Gd, Ho). [Copyright &y& Elsevier]

Abstract: The influence of pressure on the formation of U magnetic moments and mediation of exchange interactions are two principal aspects of the complex role of the 5f-ligand hybridization in magnetism of U intermetallics. Application of external pressure yields changes of interatomic distances, which are the crucial parameters controlling the hybridization. We report on pressure experiments with a 5f-electron ferromagnet UPtAl (T C=42.5K, M s=1.4 μ B/f.u. at ambient pressure). Application of hydrostatic pressure up to 1GPa yields decrease of the spontaneous magnetization M s with a rate dM s/dp=−0.027 μ B/GPa, whereas T C increases (dT C/dp=2.5K/GPa). Extension of the electrical resistivity measurements of UPtAl to pressures up to 22GPa reveals that the initial increase of T C with pressure continues up to 6GPa, where T C reaches the maximum value, and decreases with further increasing pressure. The drastic change of the R(T) curve at 17GPa is presumably connected with suppression of ferromagnetism in UPtAl. [Copyright &y& Elsevier]

RE 2 Pd 2 In, RE 2 Pd 2 Sn compounds (RE = rare earth) absorb, depending on the rare earth (RE) element, different amounts of hydrogen. The parent compounds RE 2 Pd 2 In show the linear decrease of both lattice parameters and the unit cell volume with the increasing atomic number of RE, attributed to the lanthanide contraction. All the compounds absorb at least 2 H/f.u.; the tetragonal structure is merely expanded. The expansion is anisotropic (Δ c / c > Δ a / a ), and for RE = Tb, Dy, Ho, and Er the lattice even contracts along the a -axis (Δ a / a < 0), whereas Δ c / c still weakly increases. A higher H concentration can be achieved in the compounds with light rare earths (La, Nd, both for In and Sn), which then become amorphous. The magnetic ordering temperatures of all studied RE 2 Pd 2 In compounds are dramatically reduced by the hydrogenation, typically to the temperature range below 1.8 K. [ABSTRACT FROM AUTHOR]