Fingerprint of Non-Hermiticity in d-wave Altermagnet

Abstract

We develop the non-Hermitian counterpart of a new class of collinear magnets, dubbed altermagnets, delineated by net zero magnetization with momentum-dependent spin-splitting bands. The application of an imaginary gauge field in a two-dimensional $d$-wave altermagnet injects a non-reciprocal intercell hopping without hosting exceptional points (EPs). This non-Hermitian phase hosts a point gap which remains robust in the presence and absence of Rashba spin-orbit coupling. By attaching a ferromagnetic lead with the altermagnet, we uncover the emergence of two pairs of second-order EPs. We establish that each of the EPs is associated with a half-integer quantized topological charge, a hallmark signature of the non-Hermitian topology. The existence of this non-Hermitian exceptional phase has been further confirmed by linear variation with the respective momentum and coalescence of the spin expectation value at the EPs. Finally, we demonstrate that the application of a planar magnetic field to the junction not only tunes the location of the EPs but also can annihilate a single pair or even all pairs of EPs with opposite topological charges depending upon the field strength and direction.

8 Pages, 2 Figures

References in corpus (11)

• Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
• Altermagnetism: Exploring New Frontiers in Magnetism and Spintronics
• Topologically Robust Transport of Photons in a Synthetic Gauge Field
• SNS junctions in nanowires with spin-orbit coupling: role of confinement and helicity on the sub-gap spectrum
• Majorana corner modes and tunable patterns in an altermagnet heterostructure
• Observation of Spin Splitting in Room-Temperature Metallic Antiferromagnet CrSb
• Chirality of wave functions for three coalescing levels
• Artificial gauge fields with ultracold atoms
• Emergence of tunable exceptional points in altermagnet-ferromagnet junctions
• Light-induced charge and spin Hall currents in materials with $C_{4}K$ symmetry
• Generating high-order exceptional points in coupled electronic oscillators using complex synthetic gauge fields

Cited by in corpus (8)

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• Approximate half-integer quantization in anomalous planar transport in $d$-wave altermagnets
• Non-Hermitian higher-order topological insulators enabled by altermagnet engineering
• Hexagonal Warping Control of Exceptional Points in Topological Insulator--Ferromagnetic Heterojunctions
• Time reversal reserved spin valve and spin transistor based on unconventional $p$-wave magnets
• Floquet multiple exceptional points with higher-order skin effect