Anomalous phase shift and superconducting diode effect in Josephson junctions via thin films of rare-earth intermetallic magnets

Abstract

The superconductor/ferromagnet/superconductor (S/F/S) Josephson junctions (JJs) with an anomalous ground state phase shift φ0≠0,π (φ0−S/F/S JJs) enable the implementation of the zero-field Josephson diode effect with the possibility to control the diode efficiency and polarity. It is just as important that in this case φ0 provides a coupling between the superconducting phase and the magnetization of the interlayer. Such φ0−S/F/S JJs can be used for superconducting memory and logic circuit applications. Here we present the results of theoretical calculation of the current-phase relationship (CPR), exhibiting the Josephson diode effect and φ0≠0,π, for a JJ through a specific magnetic material. As the interlayer of the JJ we consider an ultrathin film of intermetallic lanthanide (Ln)-based compound GdIr2Si2. Using the density functional theory (DFT) methods, we study the electronic structure and magnetic properties of the film. Then the effective tight-binding Hamiltonian (TBH), demonstrating high quantitative consistency with the electronic properties obtained from DFT calculations, is constructed. The TBH is used to calculate CPR in the framework of the Bogoliubov–de Gennes approach. The CPRs demonstrate a pronounced φ0 of the order of unity and a pronounced Josephson diode effect with the diode efficiency ≲0.3. Moreover, the efficiency can be controlled via rotation of in-plane magnetization in the interlayer. The prospects for utilizing alternative magnetic Ln-based materials of the LnT2X2 family (T is a transition metal and X is a p element from groups III–V) for the implementation in φ0−S/F/S JJs are also discussed.

Source-reported materials — not catalogue approval

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