Magnetic impurities in thin films and 2D Ising superconductors

Abstract

In the theory of dilute magnetic impurities in superconductors, the effect of all impurity spin-components is expressed via a single magnetic scattering rate Γm. In a more realistic setting, magnetic impurities are anisotropic. In this case, the spatial randomness of three spin-components of impurities gives rise to generally different scattering rates Γi (i=1,2,3). We explore the effects of anisotropic magnetic impurities on the in-plane critical field in 2D superconductors. We discuss singlet, triplet, and parity-mixed order parameters allowed in systems without the inversion center. Also, the addition of a small amount of magnetic impurities may cause singlet to triplet crossovers. In all cases, different components of impurity spin affect the magnetic field—temperature phase diagram differently. We show that anisotropy of the magnetic impurities can serve as a probe of unconventional triplet or parity-mixed superconductivity.

High‐Efficiency Spin–Orbit Torque Switching Using a Single Heavy‐Metal Alloy with Opposite Spin Hall Angles

“…Moreover, when electron scattering on the impurity centers of Pt 1-x Gd x layers would result in different effective magnetic field gradients due to strong SOC, then, the lateral symmetry is broken. [38,39] The presence of impurities in the Pt 1-x Gd x results in the distortions of the spin structure and that exhibits the OOP competing spins of opposite θ SHA at the Pt 1-x Gd x /Co interface as shown with illustrations in Figure 2b, which can subsequently switch the 1 nm Co layer without any external magnetic field. Furthermore, the Gd/Co/Al 2 O 3 sample does not show PMA, which confirms the small direct SOC effect of Gd atoms.…”

Multiple optical gaps and laser with magnonic pumping in 2D Ising superconductors

“…Recently discovered so-called Ising superconductivity (IS) 25,26,[37][38][39] features strong enhancement of the in-plane critical field 26,30,37,[40][41][42] , giant thickness-dependent transition state spin Hall signal 43 , electric field effect on superconductivity 26,44 , unconventional supercurrent phase 45,46 , multiple gaps 47 , collective modes 48 , and nontrivial interplay with magnetism 46,[49][50][51][52][53][54][55] . Theoretically such superconductors have been studied in the context of the unconventional pairing mechanisms [56][57][58][59][60][61][62][63] , magnetic properties 57,58,64 , parity 58,59,62,65,66 and singlet-triplet mixing superconductivity 58,59,61,62,65,…”

Magnetic field-induced "mirage" gap in an Ising superconductor

“…The presence of Ising SOC lifts the spin degeneracy in the two valleys and this results in a considerably enhanced in-plane critical magnetic field [20][21][22] beyond the Pauli limit [23,24]. Theoretical studies have mainly focused on the phase diagram [25][26][27][28][29][30][31], the occurrence of paritymixed superconductivity [26,28,32,33], or transport problems [8,34,35]. In particular, the influence of scattering on the s-wave gap was investigated [25,28,29].…”

“…Theoretical studies have mainly focused on the phase diagram [25][26][27][28][29][30][31], the occurrence of paritymixed superconductivity [26,28,32,33], or transport problems [8,34,35]. In particular, the influence of scattering on the s-wave gap was investigated [25,28,29]. Moreover, due the Ising SOC an in-plane magnetic field can mediate the conversion from singlet Cooper pairs to equal-spin triplet pairs [26-28, 30, 32].…”