Cryogenic Memory Element Based on an Anomalous Josephson Junction

Abstract

We propose a non-volatile memory element based on a lateral ferromagnetic Josephson junction with spinorbit coupling and out-of-plane magnetization. The interplay between the latter and the intrinsic exchange field of the ferromagnet leads to a magnetoelectric effect that couples the charge current through the junction and its magnetization, such that by applying a current pulse the direction of the magnetic moment in F can be switched. The two memory states are encoded in the direction of the out-of-plane magnetization. With the aim to determine the optimal working temperature for the memory element, we explore the noise-induced effects on the averaged stationary magnetization by taking into account thermal fluctuations affecting both the Josephson phase and the magnetic moment dynamics. We investigate the switching process as a function of intrinsic parameters of the ferromagnet, such as the Gilbert damping and strength of the spin-orbit coupling, and proposed a non-destructive readout scheme based on a dc-SQUID. Additionally, we analyze a way to protect the memory state from external perturbations by voltage gating in systems with a both linear-in-momentum Rashba and Dresselhaus spin-orbit coupling.

Josephson junction-based axion detection through resonant activation

“…We consider a superconductor-normal metalsuperconductor JJ (see Appendix A 1), Fig. 1(a), whose phase dynamics can be described within the resistively and capacitively shunted junction (RCSJ) model [15,27,47,48] as…”

Magnetization reversal in S/F/S Josephson junctions on a 3D topological insulator

“…Here we consider numerically the magnetization reversal by the electric current pulse. The LLG equation (5) in the dimensionless form can be written as follows:…”

“…Superconducting spintronics 1 is in the focus of active research now in view of necessity of minimizing energy consumption of devices. In particular, the ability to reverse magnetic moment of an interlayer magnet by the Josephson current has attracted much attention recently [2][3][4][5][6][7] . For the most part of the proposed setups the key ingredient allowing for the magnetization reversal is the spin-orbit coupling (SOC) taking place inside the ferromagnet or if the structure is realized as a complex interlayer consisting of the ferromagnet and a heavy metal exhibiting strong SOC.…”

Collective magnetic and plasma excitations in Josephson $ψ$ junctions

“…37,38 Similar hybridization of Josephson phase oscillations and precession of magnetic moment is predicted for the ϕ 0 junctions. [39][40][41][42][43][44][45][46] The ground state phase ϕ 0 is determined by the angle θ between the magnetic moment M orientation inside the ferromagnet and the unit vector n along the direction of the broken inversion symmetry so that ϕ 0 ∝ sin θ. As a result, the Josephson energy E = (Φ 0 I c /2πc) [1 − cos(ϕ − ϕ 0 )] becomes dependent on the magnetic moment orientation which results not only in the influence of the magnetic order on the superconducting current but also in the back-action of the Josephson current on the magnetization direction.…”