Chirality selective spin interactions mediated by the moving superconducting condensate

Abstract

We show that superconducting correlations in the presence of non-zero condensate velocity can mediate the peculiar interaction between localized spins that breaks the global inversion symmetry of magnetic moments. The proposed interaction mechanism is capable of removing fundamental degeneracies between topologically distinct magnetic textures. For the generic system of three magnetic impurities in the current-carrying superconductor we find the energy term proportional to spin chirality. In realistic superconductor/ferromagnetic/superconductor setups we reveal significant energy differences between various magnetic textures with opposite chiralities. We calculate Josephson energies of junctions through left and right-handed magnetic helices as well as through the magnetic skyrmions with opposite topological charges. Relative energy shifts between otherwise degenerate magnetic textures in these setups are regulated by the externally controlled Josephson phase difference. The suggested low-dissipative manipulation with the skyrmion position in a racetrack geometry can be used for the advanced spintronics applications. arXiv:1808.06102v2 [cond-mat.supr-con]

Magnetoelectric effects in superconductor/ferromagnet bilayers

“…P χ int is the same chiral invariant which was introduced in Ref. 62 to describe the anomalous Josephson effect in S/F/S junctions with a helix magnetic interlayer. It illustrates the universality of the chiral nature of the inverse magnetoelectric effect in superconducting hybrids with textured ferromagnets.…”

Bifurcation structure and chaos in nanomagnet coupled to Josephson junction

“…The nonlinear dynamics of the JJ is sensitive to the orientation of the magnetization [16,[25][26][27][28][29][30][31], and a rich physics has been predicted due to this type of coupling between the Josephson and magnetic subsystems: for example, supercurrent-induced magnetization dynamics [25,32,33]. In the NM-JJ system, the reversal of the magnetic moment by the supercurrent pulse [30], the appearance of Devil's staircase [24] and Kapitza pendulum effects [11,34,35], have been investigated.…”

Electrical control of magnetization in superconductor/ferromagnet/superconductor junctions on a three-dimensional topological insulator

“…By now it is well-known that current-phase relation (CPR) in Josephson junctions with multi-layered ferromagnetic interlayers is strongly sensitive to the mutual orientation of the magnetizations in the layers [1][2][3][4][5][6][7][8][9][10][11][12] . CPRs of Josephson junctions with ferromagnetic interlayers in the presence of spin-orbit coupling also depends on the magnetization orientation.…”