arXiv subjects

Mehdi Biderang

Publications and source records attributed to Mehdi Biderang.

20 records · Page 2Linked to original sources

arXiv2017

Mixed-pairing superconductivity in 5d Mott insulators with antisymmetric exchange

We investigate the potential existence of a superconducting phase in $5d$ Mott insulators with an eye to hole doped Sr$_2$IrO$_4$. Using a mean-field method, a mixed singlet-triplet superconductivity, $d + p$, is observed due to the antisymmetric exchange originating from a quasi-spin-orbit-coupling. Our calculation on ribbon geometry shows possible existence of the topologically protected edge states, because of nodal structure of the superconducting gap. These edge modes are spin polarized and emerge as zero-energy flat bands, supporting a symmetry protected Majorana states, verified by evaluation of winding number and $\mathbb{Z}_2$ topological invariant. At the end, a possible experimental approach for observation of these edge states and determination of the superconducting gap symmetry are discussed based on the quasi-particle interference (QPI) technique.

cond-mat.supr-con↗

arXiv2016

Spin Hall Conductivity in the impure two-dimensional Rashba s-wave superconductor

Based on the Kubo formula approach, the spin Hall conductivity (SHC) of a two-dimensional (2D) Rashba s-wave superconductor in the presence of nonmagnetic impurities is calculated. We will show that by increasing the superconducting gap, the SHC decreases monotonically to zero, while by decreasing the concentration of impurities at zero gap, the SHC closes to the clean limit universal value . As a function of the impurity relaxation rate at and (is the spin-orbit coupling in unit of), we will show that in the dirty limit () the SHC vanishes, and by increasing the relaxation time () the SHC depends on the value of superconducting gap (), is changed from zero for full gap to in zero gap. At low temperatures, the SHC goes to zero exponentially and near the critical temperature depending on the concentration of the scattering centers, the SHC will tend to the value of normal state. We will also show that the SHC is independent of spin-orbit coupling () in the clean limit.

cond-mat.supr-con↗