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Kagome vanadates {\it A}V$_3$Sb$_5$ display unusual low-temperature electronic properties including charge density waves (CDW), whose microscopic origin remains unsettled. Recently, CDW order has been discovered in a new material ScV$_6$Sn$_6$, providing an opportunity to explore whether the onset of CDW leads to unusual electronic properties. Here, we study this question using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The ARPES measurements show minimal changes to the electronic structure after the onset of CDW. However, STM quasiparticle interference (QPI) measurements show strong dispersing features related to the CDW ordering vectors. A plausible explanation is the presence of a strong momentum-dependent scattering potential peaked at the CDW wavevector, associated with the existence of competing CDW instabilities. Our STM results further indicate that the bands most affected by the CDW are near vHS, analogous to the case of {\it A}V$_3$Sb$_5$ despite very different CDW wavevectors., Comment: 33 pages, 4 figures

We use daily longitudinal data and a within-worker identification approach to examine the impacts of heat on labor force dynamics in Australia. High temperatures during 2001-2019 significantly reduced work attendance and hours worked, which were not compensated for in subsequent days and weeks. The largest reductions occurred in cooler regions and recent years, and were not solely concentrated amongst outdoor-based workers. Financial and Insurance Services was the most strongly affected industry, with temperatures above 38{\deg}C (100{\deg}F) increasing absenteeism by 15 percent. Adverse heat effects during the work commute and during outdoor work hours are shown to be key mechanisms.

The addition of magnetic impurities in topological insulators can drive ferromagnetic order that leads to novel quantum anomalous Hall transport well below the Curie temperature. The fragility of the quantized regime has been ascribed to the random nature of the magnetic moment distribution. Here, we refine this hypothesis by using inelastic neutron scattering and density-functional theory calculations to show that two antagonistic components define the magnetism in Mn-substituted SnTe, thereby limiting the effectiveness of dilute magnetic TIs. One component is strongly bound antiferromagnetic dimers that compete with ferromagnetic order. The other component consists of undimerized moments where ferromagnetic order develops via long-range interactions.

The body-centered-tetragonal antiferromagnet EuGa$_4$ exhibits A-type antiferromagnetic order below its N\'eel temperature $T_{\rm N} = 16.4$ K in magnetic field $H = 0$ where the moments are ferromagnetically aligned in the $ab$-plane with the Eu moments in adjacent Eu planes aligned antiferromagnetically. Previous magnetization versus field $M_{ab}(H)$ measurements revealed that the moments exhibit a spin-reorientation transition at a critical field $H_{c1}$ where the Eu moments become perpendicular to an in-plane magnetic field while still remaining in the $ab$ plane. A theory for $T=0$ K was previously presented that successfully explained the observed low-field moment-reorientation behavior at $T = 2$ K. Here we present a theory explaining the observed $T$ dependence of $M_{ab}(H,T

Extreme heat negatively impacts cognition, learning, and task performance. With increasing global temperatures, workers may therefore be at increased risk of work-related injuries and illness. This study estimates the effects of temperature on worker health using records spanning 1985-2020 from an Australian mandatory insurance scheme. High temperatures are found to cause significantly more claims, particularly among manual workers in outdoor-based industries. These adverse effects have not diminished across time, with the largest effect observed for the 2015-2020 period, indicating increasing vulnerability to heat. Within occupations, the workers most adversely affected by heat are female, older-aged and higher-earning. Finally, results from firm-level panel analyses show that the percentage increase in claims on hot days is largest at "safer" firms.

We report neutron-diffraction results on single-crystal CaMn$_2$P$_2$ containing corrugated Mn honeycomb layers and determine its ground-state magnetic structure. The diffraction patterns consist of prominent (1/6, 1/6, $L$) reciprocal lattice unit (r.l.u.; $L$ = integer) magnetic Bragg reflections, whose temperature-dependent intensities are consistent with a first-order antiferromagnetic phase transition at the N\'eel temperature $T_{\rm N} = 70(1)$ K. Our analysis of the diffraction patterns reveals an in-plane $6\times6$ magnetic unit cell with ordered spins that in the principal-axis directions rotate by 60-degree steps between nearest neighbors on each sublattice that forms the honeycomb structure, consistent with the $P_Ac$ magnetic space group. We find that a few other magnetic subgroup symmetries ($P_A2/c$, $P_C2/m$, $P_S\bar{1}, P_C2, P_Cm, P_S1$) of the paramagnetic $P\bar{3}m11^\prime$ crystal symmetry are consistent with the observed diffraction pattern. We relate our findings to frustrated $J_1$-$J_2$-$J_3$ Heisenberg honeycomb antiferromagnets with single-ion anisotropy and the emergence of Potts nematicity

Billions of people live in urban poverty, with many forced to reside in disaster-prone areas. Research suggests that such disasters harm child nutrition and increase adult morbidity. However, little is known about impacts on mental health, particularly of people living in slums. In this paper we estimate the effects of flood disasters on the mental and physical health of poor adults and children in urban Indonesia. Our data come from the Indonesia Family Life Survey and new surveys of informal settlement residents. We find that urban poor populations experience increases in acute morbidities and depressive symptoms following floods, that the negative mental health effects last longer, and that the urban wealthy show no health effects from flood exposure. Further analysis suggests that worse economic outcomes may be partly responsible. Overall, the results provide a more nuanced understanding of the morbidities experienced by populations most vulnerable to increased disaster occurrence., Comment: 41 pages, 1 figure, 6 tables, 10 Appendix tables

The empirical evidence suggests that key accumulation decisions and risky choices associated with economic development depend, at least in part, on economic preferences such as willingness to take risk and patience. This paper studies whether temperature could be one of the potential channels that influences such economic preferences. Using data from the Indonesia Family Life Survey and NASAs Modern Era Retrospective Analysis for Research and Applications data we exploit quasi exogenous variations in outdoor temperatures caused by the random allocation of survey dates. This approach allows us to estimate the effects of temperature on elicited measures of risk aversion, rational choice violations, and impatience. We then explore three possible mechanisms behind this relationship, cognition, sleep, and mood. Our findings show that higher temperatures lead to significantly increased rational choice violations and impatience, but do not significantly increase risk aversion. These effects are mainly driven by night time temperatures on the day prior to the survey and less so by temperatures on the day of the survey. This impact is quasi linear and increasing when midnight outdoor temperatures are above 22C. The evidence shows that night time temperatures significantly deplete cognitive functioning, mathematical skills in particular. Based on these findings we posit that heat induced night time disturbances cause stress on critical parts of the brain, which then manifest in significantly lower cognitive functions that are critical for individuals to perform economically rational decision making., Comment: 48 pages, 5 figures, 4 Appendix Figures

The thermodynamic properties of a nonrelativistic free-electron Fermi gas is of fundamental interest in condensed matter physics. Properties previously studied in three-dimensions (3D) in the low- and high-temperature limits include the internal energy, heat capacity, zero-field magnetic spin susceptibility, and pressure. Here we report solutions for the temperature dependence spanning these two temperature regimes of the chemical potential, internal energy, magnetic susceptibility, and the heat capacity at constant volume in 1D, 2D, and 3D. Also calculated are the pressure, enthalpy, heat capacity at constant pressure, isothermal compressibility, and thermal expansion coefficient versus temperature in 2D and 3D. Of primary interest here are the detailed dimension-dependent crossovers of these properties between the degenerate and nondegenerate temperature regime, which are graphically illustrated for each of the above properties., Comment: 15 pages, 10 captioned figures, 33 references. Title changed, Introduction extended, Appendix material moved to Section II

A recently-developed molecular field theory (MFT) has been used to fit single-crystal magnetic susceptibility chi versus temperature T data below the respective antiferromagnetic ordering temperatures TN for a variety of collinear and coplanar noncollinear Heisenberg antiferromagnets. The spins in the system are assumed to interact by Heisenberg exchange and to be identical and crystallographically equivalent. The fitting parameters for chi(T) of collinear antiferromagnets are measurable quantities: the Weiss temperature theta_p in the Curie-Weiss law, TN, chi(TN), and the spin S. For coplanar noncollinear helix and cycloid structures, an additional fitting parameter is the turn angle between layers of ferromagnetically-aligned spins. Here MFT fits to anisotropic chi(T) data from the literature for single crystals of the collinear antiferromagnets GdCu2Si2 and CuO and the noncollinear antiferromagnets LiCr2As2 with a 120 degree cycloidal structure and alpha-CaCr2O4 with a 120 degree helical structure below their respective Neel temperatures are presented. The MFT fit to the anisotropic chi(T < TN) data for CuO is poor, whereas the fits to the data for GdCu2Si2, LiCrO2, and alpha-CaCr2O4 are quite good. The poor fit for CuO is attributed to the influence of strong quantum fluctuations associated with the small Cu spin and the quasi-one-dimensional magnetism that are not taken into account by the MFT. The magnetic contribution to the zero-field heat capacity of the collinear antiferromagnet GdNiGe3 at T < TN is also fitted by the MFT., Comment: 8 pages, 6 captioned figures, 31 references. Accepted by Journal of Magnetism and Magnetic Materials. arXiv admin note: substantial text overlap with arXiv:1407.6353

This paper presents a novel, more efficient proper orthogonal decomposition (POD) based reduced-order model (ROM) for compressible flows. In this POD model the governing equations, i.e., the conservation of mass, momentum, and energy equations were written using specific volume instead of density. This substitution allowed for the pre-computation of the coefficients of the system of ODEs that make up the reduced-order model. Several methods were employed to enhance the stability of the ODE solver: the penalty method to enforce boundary conditions, artificial dissipation, and a method that modifies the number of modes used in the POD approximation. This new POD-based reduced-order model was validated for four cases at both on- and off-reference conditions: a quasi-one-dimensional nozzle, a two-dimensional channel, a three-dimensional axisymmetric nozzle, and a transonic fan. The speedup obtained by using the POD-based ROM vs. the full-order model exceeded four orders of magnitude in all cases tested., Comment: 45 pages, 20 figures

A prototypical model of a one-dimensional metallic monatomic solid containing noninteracting electrons is studied, where the argument of the cosine potential energy periodic with the lattice contains the first reciprocal lattice vector G1 = 2pi/a, where a is the lattice constant. The time-independent Schrodinger equation can be written in reduced variables as a Mathieu equation for which numerically-exact solutions for the band structure and wave functions are obtained. The band structure has band gaps that increase with increasing amplitude q of the cosine potential. In the extended-zone scheme, the energy gaps decrease with increasing index n of the Brillouin-zone boundary ka = n pi where k is the crystal momentum of the electron. The wave functions at the bottoms and tops of the bands are found to be real or imaginary, respectively, corresponding to standing waves at these energies. Irrespective of the wave vector k within the first Brillouin zone, the electron probability density is found to be periodic with the lattice. The Fourier components of the wave functions are derived versus q, which reveal multiple reciprocal-lattice-vector components with variable amplitudes in the wave functions unless q = 0. The magnitudes of the Fourier components are found to decrease exponentially as a power of n for n ~ 3 to 45 for ka = pi/2 and q = 2 and a precise fit is obtained to the data. The probability densities and probability currents obtained from the wave functions are also discussed. The probability currents are found to be zero for crystal momenta at the tops and bottoms of the energy bands, because the wave functions for these crystal momenta are standing waves. Finally, the band structure is calculated from the central equation and compared to the numerically-exact band structure., Comment: 13 pages, 15 captioned figures

The repulsive-potential Kronig-Penney (KP) model for a one-dimensional band structure is well known. However, real metals contain positively-charged ions resulting in attractive potential wells seen by the metallic electrons. Here we consider the latter case in detail. The square-well version of the KP model is considered first, for which the band structure and wave functions for different potential-well depths are derived. Then an extended treatment of the attractive Dirac-comb version of the KP model is presented. For the nearly-free-electron case, the band structure exhibits a negative-energy band in addition to positive-energy bands. The wave functions, electron densities of states, effective masses, and group velocities are derived for the positive-energy band states. The wave functions of the negative-energy band states are also calculated and found to be quite different from the sinusoidal wave functions for the positive-energy band and band-gap states. High-degeneracy bound states are found at negative energies and their wave functions are derived., Comment: 23 pages, 23 captioned figures, 4 table, 33 references. New title, improved clarity, additional topics covered

We report the synthesis and properties of a new layered tetragonal ternary compound CsMn$_4$As$_3$ (structure: KCu$_4$S$_3$-type, space group: $P4/mmm$, No. 123 and $Z = 2$). The material is a small band-gap semiconductor and exhibits an antiferromagnetic ground state associated with Mn spins. The compound exhibits a signature of a distinct magnetic moment canting event at 150(5)~K with a canting angle of $\approx 0.3^{\circ}$. Although, some features of the magnetic characteristics of this new compound are qualitatively similar to those of the related BaMn$_2$As$_2$, the underlying Mn sublattices of the two materials are quite different. While the Mn square-lattice layers in BaMn$_2$As$_2$ are equally spaced along the $c$-direction with the interlayer distance $d_{\rm L\,Ba} = 6.7341(4)$ Ang., the Mn sublattice forms bilayers in CsMn$_4$As$_3$ with the interlayer distance within a bilayer $d_{\rm L\,Cs} = 3.1661(6)$ Ang. and the distance between the two adjacent bilayers $d_{\rm B} = 7.290(6)$ Ang. This difference in the Mn sublattice is bound to significantly alter the energy balance between the $J_{1}$, $J_{2}$ and $J_{c}$ exchange interactions within the J1-J2-Jc model compared to that in BaMn$_2$As$_2$ and the other related 122 compounds including the well-known iron-arsenide superconductor parent compound BaFe$_2$As$_2$. Owing to the novelty of its transition metal sublattice, this new addition to the family of tetragonal materials related to the iron-based superconductors brings prospects for doping and pressure studies in the search of new superconducting phases as well as other exciting correlated-electron properties., Comment: 9 pages in the published version, 8 figures

A helix has a wavevector along the z axis with the magnetic moments ferromagnetically-aligned within xy planes with a turn angle kd between the moments in adjacent planes in transverse field Hx = 0. The magnetic structure and x-axis average magnetization per spin of this system in a classical XY anisotropy field HA is studied versus kd, HA, and large Hx at zero temperature. For values of HA below a kd-dependent maximum value, the xy helix phase transitions with increasing Hx into a spin-flop (SF) phase where the ordered moments have x, y, and z components. The moments in the SF phase are taken to be distributed on either one or two xyz spherical ellipses. The minor axes of the ellipses are oriented along the z axis and the major axes along the y axis where the ellipses are flattened along the z axis due to the presence of the XY anisotropy. From energy minimization of the SF spherical ellipse parameters for given values of kd, HA and Hx, four kd-dependent SF phases are found: either one or two xyz spherical ellipses and either one or two xy fans, in addition to the xy helix phase and the paramagnetic (PM) phase with all moments aligned along Hx. The PM phase occurs via second-order transitions from the xy fan and SF phases with increasing Hx. Phase diagrams in the Hx-HA plane are constructed by energy minimization with respect to the SF phases, the xy helix phase, and the xy fan phase for four kd values. One of these four phase diagrams is compared with the magnetic properties found experimentally for the model helical Heisenberg antiferromagnet EuCo2P2 and semiquantitative agreement is found., Comment: 14 pages, 8 captioned figures

A popular classroom demonstration is to draw a cycloid on a blackboard with a piece of chalk inserted through a hole at a point P with radius r = R from the center of a wood disk of radius R that is rolling without slipping along the chalk tray of the blackboard. Here the parametric equations versus time are derived for the path of P from the superposition of the translational motion of the center of mass (cm) of the disk and the rotational motion of P about this cm for r = R (cycloid), r < R (curtate cycloid) and r > R (prolate cycloid). It is further shown that the path of P is still a cycloidal function for rolling with frictionless slipping, but where the time dependence of the sinusoidal Cartesian coordinates of the position of P is modified. In a similar way the parametric equations versus time for the orbit with respect to a star of a moon in a circular orbit about a planet that is in a circular orbit about a star are derived, where the orbits are coplanar. Finally, the general parametric equations versus time for the path of the magnetization vector during undamped electron-spin resonance are found, which show that cycloidal paths can occur under certain conditions., Comment: 9 pages, 10 figures

The absorptive and dispersive components of the frequency-dependent magnetic susceptibility both contribute to the electron-spin resonance (ESR) radio-frequency (rf) power absorption of local magnetic moments in metals according to Dyson's theory. The magnetic-field prefactor present in the expression for this power absorption has been omitted in the past when fitting Dyson's lineshape to the observed field derivative of broad ESR rf power absorption spectra but is shown here to significantly influence such fits and therefore also the quantitative physical interpretations of the temperature-dependent fit parameters., Comment: The paper is based on predictions of the Bloch equations. This is not correct for wide absorption lines for which the modified Bloch equations must be used instead. The correct theory is given in arXiv:1809.02653v4

A comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T, magnetic field H, and anisotropy field parameter hA1 is presented for systems comprised of identical crystallographically-equivalent local moments. The anisotropy field for collinear z-axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or field-induced thermal-average moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the xy plane, again with a magnitude proportional to the moment. Properties studied include the zero-field Neel temperature TN, ordered moment, heat capacity and anisotropic magnetic susceptibility of the AFM phase versus T with moments aligned either along the z axis or in the xy plane. Also determined are the high-field magnetization perpendicular to the axis or plane of collinear or planar noncollinear AFM ordering, the high-field magnetization along the z axis of a collinear z-axis AFM, spin-flop (SF), and paramagnetic (PM) phases, and the free energies of these phases versus T, H, and hA1. Phase diagrams at T = 0 in the Hz-hA1 plane and at T > 0 in the Hz-T plane are constructed for spins S = 1/2. For hA1 = 0 the SF phase is stable at low field and the PM phase at high field with no AFM phase present. As hA1 increases, the phase diagram contains the AFM, SF and PM phases. Further increases in hA1 lead to the disappearance of the SF phase and the appearance of a tricritical point on the AFM-PM transition curve. Applications of the theory to extract hA1 from experimental low-field magnetic susceptibility data and high-field magnetization versus field isotherms for single crystals of AFMs are discussed., Comment: 41 pages, 35 captioned figures including 81 subfigures