Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSuperconductivity in the noncentrosymmetric half-Heusler compound LuPtBi : A possible topological superconductor
174
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report superconductivity in the ternary half-Heusler compound LuPtBi, with Tc = 1.0 K and Hc2 = 1.6 T. The crystal structure of LuPtBi lacks inversion symmetry, hence the material is a noncentrosymmetric superconductor. Magnetotransport data show semimetallic behavior in the normal state, which is evidence for the importance of spin-orbit interaction. Theoretical calculations indicate that the strong spin-orbit interaction in LuPtBi should cause strong band inversion, making this material a promising candidate for 3D topological superconductivity.
rate research
Read More
The superconducting gap structure of a topological crystalline insulator (TCI) candidate ZrRuAs ($T^{rm on}_{rm c}$ = 7.9(1) K) with a noncentrosymmetric crystal structure has been investigated using muon spin rotation/relaxation ($mu$SR) measurements in transverse-field (TF) and zero-field (ZF) geometries. We also present the results of magnetization, electrical resistivity and heat capacity measurements on ZrRuAs, which reveal bulk superconductivity below 7.9~K. The temperature dependence of the effective penetration depth obtained from the analysis of the TF-$mu$SR spectra below $T_{rm c}$ is well described by an isotropic $s$-wave gap model as also inferred from an analysis of the heat capacity in the superconducting state. ZF $mu$SR data do not show any significant change in the muon spin relaxation rate above and below the superconducting transition temperature indicating that time-reversal symmetry is preserved in the superconducting state of this material.
The noncentrosymmetric superconductor Mo$_3$Rh$_2$N, with $T_c = 4.6$ K, adopts a $beta$-Mn-type structure (space group $P$4$_1$32), similar to that of Mo$_3$Al$_2$C. Its bulk superconductivity was characterized by magnetization and heat-capacity measurements, while its microscopic electronic properties were investigated by means of muon-spin rotation and relaxation ($mu$SR). The low-temperature superfluid density, measured via transverse-field (TF)-$mu$SR, evidences a fully-gapped superconducting state with $Delta_0 = 1.73 k_mathrm{B}T_c$, very close to 1.76 $k_mathrm{B}T_c$ - the BCS gap value for the weak coupling case, and a magnetic penetration depth $lambda_0 = 586$ nm. The absence of spontaneous magnetic fields below the onset of superconductivity, as determined by zero-field (ZF)-$mu$SR measurements, hints at a preserved time-reversal symmetry in the superconducting state. Both TF-and ZF-$mu$SR results evidence a spin-singlet pairing in Mo$_3$Rh$_2$N.
By employing a series of experimental techniques, we provide clear evidence that CaPtAs represents a rare example of a noncentrosymmetric superconductor which simultaneously exhibits nodes in the superconducting gap and broken time-reversal symmetry (TRS) in its superconducting state (below $T_c$ $approx$ 1.5 K). Unlike in fully-gapped superconductors, the magnetic penetration depth $lambda(T)$ does not saturate at low temperatures, but instead it shows a $T^2$-dependence, characteristic of gap nodes. Both the superfluid density and the electronic specific heat are best described by a two-gap model comprising of a nodeless gap and a gap with nodes, rather than by single-band models. At the same time, zero-field muon-spin spectra exhibit increased relaxation rates below the onset of superconductivity, implying that TRS is broken in the superconducting state of CaPtAs, hence indicating its unconventional nature. Our observations suggest CaPtAs to be a new remarkable material which links two apparently disparate classes, that of TRS-breaking correlated magnetic superconductors with nodal gaps and the weakly-correlated noncentrosymmetric superconductors with broken TRS, normally exhibiting only a fully-gapped behavior.
We report the electronic structure, synthesis, and measurements of the magnetic, transport, and thermal properties of the polycrystalline noncentrosymmetric compound Re$_{6}$Zr. We observed a bulk superconducting transition at temperature $T_{c}$ $sim$ 6.7 K, and measured the resistivity, heat capacity, thermal conductivity, and the London penetration depth below the transition, as well as performed doping and pressure studies. From these measurements we extracted the critical field, and the superconducting parameters of Re$_{6}$Zr. Our measurements indicate a relatively weak to moderate contribution from a triplet component to the order parameter, and favor a full superconducting gap, although we cannot exclude the existence of point nodes based on our data.
We investigate the superconducting gap function of topological superconductor PbTaSe$_2$. Temperature, magnetic field, and three-dimensional (3D) field-angle dependences of the specific heat prove that the superconductivity of PbTaSe$_2$ is fully-gapped, with two isotropic $s$-wave gaps. The pair-breaking effect is probed by systematically increasing non-magnetic disorders through H$^+$-irradiations. The superconducting transition temperature, $T_{rm{c}}$, is found to be robust against disorders, which suggests that the pairing should be sign-preserved rather than sign-reversed.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
