Majorana Kramers doublets in d x 2 − y 2 -wave superconductors with Rashba spin-orbit coupling

In this work, we show that a quasi-one-dimensional ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconductor with Rashba spin-orbit coupling is a DIII class, time-reversal invariant, topological superconductor (TS), which supports a Majorana Kramers Doublet (MKD) at each end of the TS. A MKD is a pair of Majorana end states (MESs) protected by time-reversal symmetry (TRS). An external magnetic field breaks TRS and drives the system from DIII to D class in which case a single MES appears at each end of the TS. We show that a MKD induces resonant Andreev reflection with zero-bias conductance peak of $4{e}^{2}/h$. Experimental realizations of the proposed model are discussed.