Yu-Shiba-Rusinov bound states induced by a spin flipper in the vicinity of a s-wave superconductor

Abstract

We theoretically study the formation and characteristics of Yu-Shiba-Rusinov bound states within the superconducting gap using a BTK approach in presence of a spin flipper (high spin magnetic impurity). We focus on the zero energy in the conductance spectra and show how a peak is formed at E = 0 due to flipping of the magnetic impurity spin, but for no flip case a dip forms at E = 0 in the conductance spectra. This E = 0 conductance peak is almost quantized at 2e2/h values, however it arises due to non-topological reasons in contrast to the E = 0 peak formed due to Majorana states.

Spin-dependent zero-bias peak in a hybrid nanowire-quantum dot system: Distinguishing isolated Majorana fermions from Andreev bound states

“…In these hybrid devices, manifestation of a robust zero-bias conductance peak (ZBCP) has been considered as an experimental signature of the presence of highly nonlocal MBSs emerging at the opposite ends of a nanowire [11][12][13][14][15] . However, it was argued later on that other physical mechanisms such as disorder 16 , Kondo effect 17,18 and formation of Andreev bound states (ABSs) [19][20][21][22][23][24][25][26][27][28] can be responsible for the appearance of analogs of ZBCP. In particular, there is ongoing controversy 29 whether near zero-energy ABS, constituted by weakly overlapping MBSs, can mimic robust 2e 2 /h ZBCP 22,23 .…”

Quantized Josephson phase battery

“…being the kinetic energy of the electron with mass m , V denotes the strength of δ potentials at the interfaces between ferromagnets and superconductor, J 0 denotes the strength of the exchange coupling between electron/hole with spin s and spin-flipper [35,36] with spin S. ψ(x) defines a four-component spinor, while E F is the Fermi energy, σ's are Pauli spin matrices and Î is a 2 × 2 identity matrix. The magnetization vector ( h) of the left ferromagnetic layer (F 1 ) is at an angle θ with the z-axis in the y-z plane, while that of the right h Fig.…”

Spin-flip scattering engendered quantum spin torque in a Josephson junction

“…[21], and finally in modeling the occurrence of Yu-Shiba-Rusinov (YSR) bound states in at the interface of normal metal-superconductor junction, see Ref. [26].…”

“…The aforesaid method of addressing spin-flip scattering process is not unique to our work, many other papers have used the same model of spin-flip scattering in different context, mention may be made of the first paper which introduced this model, see [22], to model of quantum spinflip scattering in graphene, see [25], in modelling the quantum spin-flip scattering in a Josephson junction, see [21], and finally in modelling the occurrence of Yu-Shiba-Rusinov (YSR) bound states in at the interface of normal metal-superconductor junction, see [26].…”