An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature T_N = 47 K compared to the ferromagnetic Weiss temperature theta = 12 K. We show that this is, surprisingly, consistent with mean field theory. A first-order field-induced magnetic transition is observed at T < T_N with an unusual temperature dependence of the transition field. A dramatic magnetic field-induced reduction of the electronic specific heat coefficient at 1.8-5.0 K by 38% at 9 T is observed. In addition, a strong positive magnetoresistance and a large change in the Hall coefficient occur below 25 K. Band structure calculations indicate that the Fermi energy lies on a steep edge of a narrow peak in the density of states.
Low-temperature electronic heat transport in La_{2-x}Sr_{x}CuO_{4} single crystals: Unusual low-energy physics in the normal and superconducting states
Local-moment ferromagnetism and unusual magnetic domains in Fe$_{1/4}$TaS$_{2}$ crystals
用磁光成像和射频磁化率（$χ$）研究了Fe $_{1/4}$ TaS $_{2}$单晶。实时MO图像揭示了不寻常的，缓慢的动态树突状域的形成，其细节是强烈依赖于磁和热的历史。$χ(T)$的测量结果表明，在$T\approx 155$ K下，$χ(T)$表现出定义明确的局部磁矩铁磁转变，以及在50 K $<T<$ 60 K下的热滞后。该温度范围对应于由MO确定的畴形成温度。这些观测结果为Fe $_{1/4}$ TaS $_{2}$晶体中的局部磁矩铁磁性提供了强有力的证据，该晶体具有较大的温度依赖性磁各向异性。
Polycrystalline La$_{7}$Ir$_{3}$ is reported to show superconductivity breaking time-reversal symmetry while also having an isotropic $s$-wave gap. Single crystals of this noncentrosymmetric superconductor are highly desirable to understand the nature of the electron pairing mechanism in this system. Here we report the growth of high-quality single crystals of La$_{7}$Ir$_{3}$ by the Czochralski method. The structural and superconducting properties of these large crystals have been investigated using x-rays, magnetization, resistivity and heat capacity measurements. We observe a clear anisotro…
We report synthesis, structural details and electrical transport properties of topological insulator Bi2Te3. The single crystalline specimens of Bi2Te3 are obtained from high temperature (950C) melt and slow cooling (2C/hour). The resultant crystals were shiny, one piece (few cm) and of bright silver color. The Bi2Te3 crystal is found to be perfect with clear [00l] alignment. The powder XRD pattern being carried out on crushed crystals showed that Bi2Te3 crystallized in R3m symmetry with a = b = 4.3866(2) A, c = 30.4978(13) A and Gamma = 120degree. The Bi position is refined to (0, 0, 0.4038 (…
We investigate single crystalline samples of Ce$_{1-x}$Nd$_{x}$RhIn$_{5}$ by means of X-ray diffraction, microprobe, magnetic susceptibility, heat capacity, and electrical resistivity measurements. Our data reveal that the antiferromagnetic transition temperature of CeRhIn$_{5}$, $T_{N}^{\mathrm{Ce}} = 3.8$ K, is linearly suppressed with $x_{\mathrm{Nd}}$, by virtue of the "Kondo hole" created by Nd substitution. The extrapolation of $T^{\mathrm{Ce}}_{N}$ to zero temperature, however, occurs at $x_{c} \sim 0.3$, which is below the 2D percolation limit found in Ce$_{1-x}$La$_{x}$RhIn$_{5}$. Thi…
First-principles calculations within the DFT are employed to investigate the relationship between the electronic structure and the unexpected features of the hexagonal cell parameters of YbAuIn and Yb$_{3}$AuGe$_{2}$In$_{3}$. Calculations indicate that YbAuIn is an intermediate valent system with one Yb 4\textit{f} state pinned to the Fermi level, while Yb$_{3}$AuGe$_{2}$In$_{3}$ is closer to integer valency with all Yb 4\textit{f} states occupied. Structural relaxations performed on LaAuIn and LuAuIn analogs reveal that expansion of the \textit{c}-parameter in Yb$_{3}$AuGe$_{2}$In$_{3}$ is at…
The Kitaev quantum spin liquid displays the fractionalization of quantum spins into Majorana fermions. The emergent Majorana edge current is predicted to manifest itself in the form of a finite thermal Hall effect, a feature commonly discussed in topological superconductors. Here we report on thermal Hall conductivity $κ_{xy}$ measurements in $α$-RuCl$_3$, a candidate Kitaev magnet with the two-dimensional honeycomb lattice. In a spin-liquid (Kitaev paramagnetic) state below the temperature characterized by the Kitaev interaction $J_K/k_B \sim 80$ K, positive $κ_{xy}$ develops gradually upon c…
We present inelastic neutron scattering results of phonons in (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te powders, with $x=0$ and 0.3. The $x=0$ sample is a topological crystalline insulator, and the $x=0.3$ sample is a superconductor with a bulk superconducting transition temperature $T_c$ of 4.7 K. In both samples, we observe unexpected van Hove singularities in the phonon density of states at energies of 1--2.5 meV, suggestive of local modes. On cooling the superconducting sample through $T_c$, there is an enhancement of these features for energies below twice the superconducting-gap energy. We …
We present both time-averaged and time-resolved transport measurements of a two-dimensional electron (Wigner) crystal on the surface of superfluid helium confined in a narrow microchannel. We find that the field-current characteristics of the driven crystal obtained by the time-averaged measurements exhibit oscillations and negative differential conductivity. This unusual transport behavior was observed previously by Glasson et al. [Phys. Rev. Lett. 87, 176802 (2001)] and was attributed to a nonequilibrium transition of the electron system to a novel dynamically ordered phase of current filame…
Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single crystal X-ray data to be isotypic with the ThB2C-type (space group R3m, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a = 0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z=9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 K to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic orderin…
Uranium dipnictide USb$_2$ reflects enigmatic properties posing a substantial challenge for a microscopic modeling. Among others, it develops a nonstandard antiferromagnetic order of a $\uparrow\downarrow\downarrow\uparrow$-type along [001] crystallographic direction, and under pressure it undergoes transition to the ferromagnetic phase. Here we propose a minimal low-energy model of USb$_2$ which, as we demonstrate at the mean-field level, accommodates physical mechanism for mentioned observations. Relying on the obtained results we also comment on the features of magnetism observed in other U…
We study the electronic structure, magnetic state, and phase stability of paramagnetic BiNiO$_3$ near a pressure-induced Mott insulator-to-metal transition (MIT) by employing a combination of density functional and dynamical mean-field theory. We obtain that BiNiO$_3$ exhibits an anomalous negative-charge-transfer insulating state, characterized by charge disproportionation of the Bi $6s$ states, with Ni$^{2+}$ ions. Upon a compression of the lattice volume by $\sim$4.8\%, BiNiO$_3$ is found to make a Mott MIT, accompanied by the change of crystal structure from triclinic $P\bar{1}$ to orthorh…
Bulk La_wCoO3 particles with w=1.1, 1.0, 0.9, 0.8, and 0.7 were synthesized using starting materials with varying molar ratios of La2O3 and Co3O4. The resulting particles are characterized as LaCoO3 crystals interfaced with a crystalline Co3O4 phase. X-ray and neutron scattering data show little effect on the average structure and lattice parameters of the LaCoO3 phase resulting from the Co3O4 content, but magnetization data indicate that the amount of Co3O4 strongly affects the ferromagnetic ordering at the interfaces below T_C ~89K. In addition to ferromagnetic long-range order, LaCoO3 exhib…
The magnetization, crystal structure, and thermal expansion of a nearly stoichiometric Sr$_{1.04(3)}$Er$_{2.09(6)}$O$_{4.00(1)}$ single crystal have been studied by PPMS measurements and in-house and high-resolution synchrotron X-ray powder diffraction. No evidence was detected for any structural phase transitions even up to 500 K. The average thermal expansions of lattice constants and unit-cell volume are consistent with the first-order Grüneisen approximations taking into account only the phonon contributions for an insulator, displaying an anisotropic character along the crystallographic \…
To probe the peculiar excitations spinons and magnetic monopoles in the quantum spin ice candidate Pr2Zr2O7, we studied the low-temperature thermal Hall conductivity (\k{appa}xy) and thermal conductivity (\k{appa}xx) of Pr2Zr2O7 single crystal with magnetic fields applied along the [111] axis. The magnetic field dependencies of \k{appa}xx suggest the roles of magnetic excitations in thermal conductivity, that is, the emergent magnetic monopoles can transport heat at T > 1.4 K and spinons mainly scatter phonons at lower temperatures. The finite \k{appa}xy was observed at low fields of several T…
Contribution to thermal conductivity from conduction electron scattering on crystal field magnetic excitations is calculated and analyzed for normal rare-earth inter-metallic paramagnets. It is shown that in temperatures much lower than Debye temperature $\TD$ its behavior essentially depends on the ground state of magnetic ion in crystal field and on the excitation energy in relation to $\TD$\,. Combined effect from the electron scattering on the crystal-field excitations, on acoustic phonons, and on nonmagnetic impurities is discussed in reference to CF splitting character and to the relativ…
The electric-field control of $d$-electron magnetism in multiferroic transition metal oxides is attracting widespread interest for the underlying fundamental physics and for next generation spintronic devices. Here, we report an extensive study of the $3d$ magnetism in magnetoelectric Ga$_{0.6}$Fe$_{1.4}$O$_3$ (GFO) epitaxial films by polarization dependent x-ray absorption spectroscopy. We found a non-zero integral of the x-ray magnetic circular dichroism, with a sign depending upon the relative orientation between the external magnetic field and the crystallographic axes. %By reliably enlarg…
