# Phase-Rotated Altermagnets as Chern Valves for Topological Transport

## TL;DR

This paper proposes a new way to control topological transport using altermagnets with adjustable crystal phases, enabling programmable conductance without magnetic fields.

## Contribution

A novel symmetry-driven mechanism for programmable topological transport using phase-rotated altermagnets.

## Key findings

- Phase rotation of altermagnetic electrodes tunes chiral edge channels and discrete conductance steps.
- Thermoelectric Hall coefficient inversion is achieved without external magnetic fields or net magnetization.
- A compact Dirac model explains quantized switching and resilience to disorder.

## Abstract

Motivated by the
emerging control of Berry-curvature
textures in
altermagnets, we explore a two-terminal configuration where a topological-insulator
film is interfaced with two altermagnetic electrodes whose crystalline
phases can be rotated independently. The proximity coupling imprints
each altermagnet’s momentum-dependent spin texture onto the
Dirac surface states, giving rise to an angular mass whose sign follows
the lattice orientation. Adjusting the phase of one electrode redefines
this mass pattern, thereby tuning the number and spatial distribution
of chiral edge channels. This results in discrete conductance steps
and a reversible inversion of the thermoelectric Hall coefficientachieved
without external magnetic fields or net magnetization. A compact Dirac
model captures both the quantized switching and its resilience to
moderate disorder. Overall, this symmetry-driven mechanism provides
a practical and low-dissipation route to programmable topological
transport via lattice rotation.