Generalized DC and AC Josephson effects in antiferromagnets and in antiferromagnetic d-wave superconductors

Abstract

The Josephson effect is generally described as Cooper pair tunneling, but it can also be understood in a more general context. The DC Josephson effect is the pseudo-Goldstone boson of two coupled systems with a broken continuous abelian U(1) symmetry. Hence, an analog should exist for systems with broken continuous non-Abelian symmetries. To exhibit the generality of the phenomenon and make predictions from a realistic model, we study tunneling between antiferromagnets and also between antiferromagnetic d-wave superconductors. Performing a calculation analogous to that of Ambegaokar and Baratoff for the Josephson junction, we find an equilibrium current of the staggered magnetization through the junction that, in antiferromagnets, is proportional to s_L X s_R where s_L and s_R are the Neel vectors on either sides of the junction. Microscopically, this effect exists because of the coherent tunneling of spin-one particle-hole pairs. In the presence of a magnetic field which is different on either sides of the junction, we find an analog of the AC Josephson effect where the angle between Neel vectors depends on time. In the case of antiferromagnetic d-wave superconductors we predict that there is a contribution to the critical current that depends on the antiferromagnetic order and a contribution to the spin-critical current that depends on superconducting order. The latter contributions come from tunneling of the triplet Cooper pair that is necessarily present in the ground state of an antiferromagnetic d-wave superconductor. All these effects appear to leading order in the square of the tunneling matrix elements.

10 pages

References in corpus (11)

• Electronic Orbital Currents and Polarization in Mott Insulators
• Equilibrium spin currents and magnetoelectric effect in magnetic nanostructures
• Spin Josephson effect in ferromagnet/ferromagnet tunnel junctions
• Mean-field study of the interplay between antiferromagnetism and d-wave superconductivity
• Spin-dependent quasiparticle reflection and bound states at interfaces with itinerant antiferromagnets
• Backward Scattering and Coexistent State in Two-Dimensional Electron System
• Tunneling currents in ferromagnetic systems with multiple broken symmetries
• Spontaneous spin current due to triplet superconductor--ferromagnet interfaces
• Equilibrium spin current through the tunnelling junctions
• Quantum dynamics of tunneling between ferromagnets
• Field theoretic description of the abelian and non-abelian Josephson effect

Cited by in corpus (6)

• Nematic versus ferromagnetic spin filtering of triplet Cooper pairs in superconducting spintronics
• Dissipationless Spin Current between Two Coupled Ferromagnets
• Flux Quantization Due to Monopole and Dipole Currents
• Josephson-like spin current in junctions composed of antiferromagnets and ferromagnets
• Monopole Josephson Effects in a Dirac Spin Liquid
• Theory of generalized Josephson effects