Raman scattering has been employed to investigate lattice and magnetic excitations of the honeycomb Kitaev material $\alpha$-RuCl$_3$ its Heisenberg counterpart CrCl$_3$. Our phonon spectra give evidence for a first-order structural transition from monoclinic rhombohedral structure both compounds. Significantly, only features large thermal hysteresis, consistent with formation wide phase coexistence. In related temperature interval $70-170$ K, we observe hysteretic behavior as well. The...

Measurements of the temperature and angular dependencies upper critical field ${H}_{c2}$ a stoichiometric single crystal LiFeAs in pulsed magnetic fields up to 50 T were performed using tunnel diode resonator. Complete ${H}_{c2}^{\ensuremath{\parallel}c}$$(T)$ ${H}_{c2}^{\ensuremath{\perp}c}$$(T)$ functions with ${H}_{c2}^{\ensuremath{\parallel}c}$$(0)=17\ifmmode\pm\else\textpm\fi{}1$ T, ${H}_{c2}^{\ensuremath{\perp}c}$$(0)=26\ifmmode\pm\else\textpm\fi{}1$ anisotropy parameter...

The variations of in- and inter-plane London penetration depths, $\ensuremath{\Delta}\ensuremath{\lambda}(T)$, were measured using a tunnel diode resonator in single crystals the intrinsic pnictide superconductor LiFeAs. This compound appears to be clean limit with residual resistivity 4 ($T\ensuremath{\rightarrow}0$) 8 (${T}_{c}$) $\ensuremath{\mu}\ensuremath{\Omega} $cm ratio 65 35, respectively. superfluid density...

We report on the systematic magnetization measurements performed stoichiometric Gd monopnictides, ( = N, P, As, Sb, and Bi), at temperatures between 1.6 350 K in magnetic fields up to 42 T. GdN shows ferromagnetic behaviour with a Curie temperature . The other samples order antiferromagnetically Néel 15.9, 18.7, 23.4, 25.8 for Bi, respectively. A spin - flop transition is observed low except GdN. Based molecular field approximation, nearest-neighbour next-nearest-neighbour exchange constants...

A LiFeAs single crystal with Tconset∼19.7 K was grown in a sealed tungsten crucible using the Bridgeman method. The electrical resistivity experiments revealed ratio of room temperature to residual approximately 46 and 18 for in-plane out-of plane directions, respectively. estimated anisotropic resistivity, γρ=ρc/ρab, 3.3 at Tconset. upper critical fields had large Hc2∥ab Hc2∥c values 83.4 T 72.5 T, respectively, an anisotropy is γH=Hc2∥ab/Hc2∥c∼1.15. high field value small highlight...

We report the high thermoelectric figure-of-merit (ZT) on Se-deficient polycrystalline compounds of In4Se3−x (0.02≤x≤0.5) and anisotropic electronic band structure. The Se-deficiency (x) has effect decreasing semiconducting gap increasing power factor. structure calculation for (x=0.25) exhibits localized hole bands at Γ-point Y-S symmetry line, whereas significant dispersion is observed along c-axis. Here, we propose that ZT values those are originated from as well Peierls distortion.

Ce $4d\mathrm{\text{\ensuremath{-}}}4f$ resonant angle-resolved photoemission spectroscopy was carried out to study the electronic structure of strongly correlated $4f$ electrons in a quasi-two-dimensional nonmagnetic heavy-fermion system ${\mathrm{CeCoGe}}_{1.2}{\mathrm{Si}}_{0.8}$. For first time, dispersive coherent peaks an $f$ state crossing Fermi level, so-called Kondo resonance, are directly observed together with hybridized conduction band. Moreover, experimental band dispersion is...

The thermally activated flux flow (TAFF) of a LiFeAs single crystal was studied in magnetic fields up to 9 T. energy (TAE) analyzed using conventional Arrhenius relation and modified TAFF theory. method results are better agreement with experimental data than the ones. Through analysis method, we found that superconductor is regarded as three-dimensional (3D) system region. In addition, obtained vortex-glass temperature Tg from linear region (dln ρ/dT)− 1. And fluctuation conductivity for...

The acoustic de Haas van Alphen effect of the low carrier compound CeSb has been measured by a homemade dilution refrigerator. heavy hole orbit β 4 in ferromagnetic phase clearly observed. cyclotron effective mass under magnetic field along [001] direction was 4.3 m 0 . angular dependence cross-sectional area is well explained band calculation based on p - f mixing model. Some aspects electron-strain interaction obtained oscillation intensity elastic constant are discussed.

Abstract Epitaxial MgB 2 thick films are grown on Al O 3 substrates at 600 °C by using the hybrid physical (HP)CVD technique. In order to obtain a high magnesium vapor pressure around substrates, we use special susceptor having cap and achieve very growth rate of 0.17 μm min –1 . Hexagonal‐shaped columnar structures observed cross‐sectional planar‐view transmission electron microscope (TEM) images. For 1.7 film, T c is be 40.5 K with J 1.5 × 10 6 A cm –2 30 K. The vortex pinning mechanism...

The thermal conductivity $\ensuremath{\kappa}$ of the iron-arsenide superconductor LiFeAs (${T}_{c}\ensuremath{\simeq}$ 18 K) was measured in single crystals at temperatures down to $T\ensuremath{\simeq}50$ mK and magnetic fields up $H=17$ T, very close upper critical field ${H}_{c2}\ensuremath{\simeq}18$ T. For both directions heat current, parallel perpendicular tetragonal $c$ axis, a negligible residual linear term $\ensuremath{\kappa}/T$ is found as $T\ensuremath{\rightarrow}0$, showing...

The in- and out-of-plane lower critical fields magnetic penetration depths of LiFeAs were examined. anisotropy ratio ΓHc1(0) was smaller than the expected theoretical value, increased slightly with increasing temperature from 0.6Tc to Tc. small degree numerically confirmed by considering electron correlation effect. dependence followed a power law (∼Tn) below 0.3Tc, n>3.5 for both λab λc. Based on studies iron-based superconductors, these results suggest that superconductivity can be...

We studied the electrical, thermal, and thermoelectric properties of polycrystalline compound SmNiC${}_{2}$. The electrical resistivity magnetization measurement show interplay between charge density wave at ${T}_{\mathrm{CDW}}=150$ K ferromagnetic ordering ${T}_{c}=18$ K. Below transition temperature, we observed magnon gap formation $\ensuremath{\Delta}\ensuremath{\simeq}4.3$--4.4 meV by $\ensuremath{\rho}(T)$ ${C}_{p}(T)$ measurements. is attributed to increase Seebeck coefficient...

We report results of inelastic-neutron-scattering measurements low-energy spin-wave excitations in two structurally distinct families iron-pnictide parent compounds: Na(1-{\delta})FeAs and BaFe2As2. Despite their very different values the ordered magnetic moment N\'eel temperatures, T_N, antiferromagnetic state both compounds exhibit similar spin gaps order 10 meV at Brillouin-zone center. The gap opens sharply below with no signatures a precursor temperatures between orthorhombic phase...

The thermally activated flux flow effect has been studied in epitaxial FeSe0.6Te0.4 thin film grown by a PLD method through the electrical resistivity measurement under various magnetic fields for B//c and B//ab. results showed that is well described nonlinear temperature-dependent activation energy. evaluated apparent energy U0(B) one order larger than reported double-linearity both field directions. Furthermore, shows anisotropy of 5.6 near Tc 2D-like superconducting behavior region. In...

We report on the thermally activated flux flow dependency doping dependent mixed state in NaFe1-x Co x As (x = 0.01, 0.03, and 0.07) crystals using magnetoresistivity case of B//c-axis B//ab-plane. It was found clearly that irrespective ratio, showed a distinct tail just above T c,offset associated with (TAFF) our crystals. Furthermore, TAFF region temperature dependence activation energy follows relation [Formula: see text] q 1.5 all studied The magnetic field power law where exponent α is...

We present the first direct study of charge density wave (CDW) formation in quasi-2D single layer LaTe2 using high-resolution angle resolved photoemission spectroscopy and low energy electron diffraction. CDW is driven by Fermi surface (FS) nesting, however, characterized a surprisingly smaller gap ( approximately 50 meV) than seen double RTe2 compounds, extending over entire FS. This establishes as reported semiconducting 2D system where phase FS nesting driven. In addition, dependence this...

We report the three-dimensional electronic structure of iron pnictide superconductor LiFeAs obtained by polarization-dependent angle-resolved photoemission spectroscopy. The orbital characters each Fermi surface (FS) as well band dispersions were qualitatively consistent with those derived from local density approximation calculations. It was found that FS nesting appears between a two-dimensional hole at zone center and an electron corner same ${d}_{xy}$ character. A shadow attributed to...

We report the observation of pseudogap (PG) behavior in optical conductivity an underdoped Ba0.6+δK0.4−δFe2As2 (Tonsetc ≈ 36 K) single crystal far above Tc, up to 100 K (≈3Tc). Wide separation energy scales magnetic and superconducting (SC) correlations sample enabled us establish that PG structures observed range 50–150 cm−1 are uniquely driven by SC correlation, correlation coexists separated about 700 cm−1. Theoretical calculations, based on preformed Cooper pair model, provided excellent...