Ground states and magnonics in orthogonally coupled symmetric all-antiferromagnetic junctions

Abstract

In this paper, the rich ground-state structure of orthogonally coupled symmetric all-antiferromagnetic junctions with easy-plane anisotropy is reported. A spin reorientation process rather than the traditional spin flop (SF) occurs, resulting in a phase in which N\'eel vectors preserve the mirror-reflection symmetry (termed MRS phase). The phase transitions in the ground state between SF and MRS phases can be either first or second order. After disturbed by external stimuli, magnons with different parities emerge. For in-plane dc fields, no couplings between magnons occur. When dc fields become oblique, coherent couplings between magnons with opposite parity emerge, leading to anticrossings in resonance frequencies. However, self-hybridization among magnons with the same parity never happens. More interestingly, spin waves based on MRS phases are linearly polarized and their polarization directions can be fine controlled.