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Register a new userMicroscopic investigation of superconducting properties of a strongly coupledsuperconductor IrGe via {mu}SR
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Exploring superconductors which can possess pairing mechanism other than the BCS predicted s-wave have continually attracted considerable interest. Superconductors with low-lying phonons may exhibit unconventional superconductivity as the coupling of electrons with these low-lying phonons can potentially affect the nature of the superconducting ground state, resulting in strongly coupled superconductivity. In this work, by using magnetization, AC transport, specific heat, and muon spin rotation/relaxation ($mu$SR) measurements, we report a detailed investigation on the superconducting ground state of the strongly coupled superconductor, IrGe, that has a transition temperature, T$_{C}$, at 4.7 K. Specific heat (SH), and transverse field $mu$SR is best described with an isotropic s-wave model with strong electron-phonon coupling, indicated by the values of both $Delta(0)/k_{B}T_{C}$ = 2.3, 2.1 (SH, $mu$SR), and $Delta C_{el}/gamma_{n}T_{C}$ = 2.7. Zero-field $mu$SR measurements confirm the presence of time-reversal symmetry in the superconducting state of IrGe.
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The superconducting ground state of newly reported ZrIrSi is probed by means of $mu$SR technique along with resistivity measurement. The occurrence of superconductivity at $T_mathrm{C}$ = 1.7 K is confirmed by resistivity measurement. ZF-$mu$SR study revealed that below $T_mathrm{C}$, there is no spontaneous magnetic field in the superconducting state, indicates TRS is preserved in case of ZrIrSi. From TF-$mu$SR measurement, we have estimated the superfluid density as a function of temperature, which is described by an isotropic $s-$wave model with a superconducting gap $2Delta(0)/k_mathrm{B}T_mathrm{C}$ = 5.1, indicates the presence of strong spin-orbit coupling. {it Ab-initio} electronic structure calculation indicates that there are four bands passing through the Fermi level, forming four Fermi surface pockets. We find that the low-energy bands are dominated by the $4d$-orbitals of transition metal Zr, with substantially lesser weight from the $5d$-orbitals of the Ir-atoms.
The results of heat capacity C_p(T, H) and electrical resistivity rho(T,H) measurements down to 0.35 K as well as muon spin relaxation and rotation (muSR) measurements on a noncentrosymmetric superconductor LaIrSi3 are presented. Powder neutron diffraction confirmed the reported noncentrosymmetric body-centered tetragonal BaNiSn3-type structure (space group I4,mm) of LaIrSi3. The bulk superconductivity is observed below T_c = 0.72(1) K. The intrinsic Delta C_e/gamma_n T_c = 1.09(3) is significantly smaller than the BCS value of 1.43, and this reduction is accounted by the alpha-model of BCS superconductivity. The analysis of the superconducting state C_e(T) data by the single-band alpha-model indicates a moderately anisotropic order parameter with the s-wave gap Delta(0)/k_B T_c = 1.54(2) which is lower than the BCS value of 1.764. Our estimates of various normal and superconducting state parameters indicate a weakly coupled electron-phonon driven type-I s-wave superconductivity in LaIrSi3. The muSR results also confirm the conventional type-I superconductivity in LaIrSi3 with a preserved time reversal symmetry and hence a singlet pairing superconducting ground state.
We report on muon spin rotation/relaxation and $^{119}$Sn nuclear magnetic resonance (NMR) measurements to study the microscopic superconducting and magnetic properties of the Heusler compound with the highest superconducting transition temperature, ypd ($T_c=5.4$ K). Measurements in the vortex state provide the temperature dependence of the effective magnetic penetration depth $lambda(T)$ and the field dependence of the superconducting gap $Delta(0)$. The results are consistent with a very dirty s-wave BCS superconductor with a gap $Delta(0)=0.85(3)$ meV, $lambda(0)= 212(1)$ nm, and a Ginzburg-Landau coherence length $xi_{mathrm{GL}}(0)cong 23$ nm. In spite of its very dirty character, the effective density of condensed charge carriers is high compared to the normal state. The mSR data in a broad range of applied fields are well reproduced by taking into account a field-related reduction of the effective superconducting gap. Zero-field mSR measurements, sensitive to the possible presence of very small magnetic moments, do not show any indications of magnetism in this compound.
We study superconducting properties in multilayer thin films consisting of superconducting La$_{1.85}$Sr$_{0.15}$CuO$_4$ (LSCO) and Mott insulator Sr$_2$IrO$_4$ (SIO) and report enhanced superconductivity in optimized sample. These multilayer heterostructures show an increase in superconducting transition temperature ($T_C$) as compared to the single layer LSCO films. The temperature dependence of SIO single layer is also investigated under thermal activation, Arrhenius-type behaviour, and variable-range hopping mechanisms for different temperature regimes. The decrease in $T_C$ beyond an optimum thickness of LSCO in these multilayers is analyzed in the framework of a model based on the assumption of induced superconductivity in SIO-LSCO interface due to the doping of La and/or oxygen deficiencies into SIO layers
We implement the impedance measurement technique (IMT) for characterization of interferometer-type superconducting qubits. In the framework of this method, the interferometer loop is inductively coupled to a high-quality tank circuit. We show that the IMT is a powerful tool to study a response of externally controlled two-level system to different types of excitations. Conclusive information about qubits is obtained from the read-out of the tank properties.
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