Spin-Josephson effects in exchange coupled antiferromagnetic insulators

Yizhou Liu; Gen Yin; Jiadong Zang; Roger K. Lake; Yafis Barlas

doi:10.1103/PhysRevB.94.094434

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Spin-Josephson effects in exchange coupled antiferromagnetic insulators

Yizhou Liu, Gen Yin, Jiadong Zang, Roger K. Lake, Yafis Barlas

DOI 10.1103/PhysRevB.94.094434 · Physical Review B

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Abstract

The spin superfluid analogy can be extended to include Josephson-like oscillations of the spin current. In a system of two antiferromagnetic insulators (AFMIs) separated by a thin metallic spacer, a threshold spin chemical potential established perpendicular to the direction of the Néel vector field drives terahertz oscillations of the spin current. This spin current also has a nonlinear, time-averaged component which provides a “smoking gun” signature of spin superfluidity. The time-averaged spin current can be detected via the inverse spin Hall effect in a metallic spacer with large spin-orbit coupling. The physics illustrated here with AFMIs also applies to easy-plane ferromagnetic insulators. These findings may provide a new approach for experimental verification of spin superfluidity and realization of a terahertz spin oscillator.