Manganese telluride flips its Hall signal under strain
Rice University physicists led by Pengcheng Dai report that hexagonal manganese telluride, an altermagnet whose net magnetisation sits near zero, still produces a spontaneous anomalous Hall effect. That sideways voltage appears without an external magnetic field and shows that time-reversal symmetry is broken even though opposing spins largely cancel. First author Zhaoyu Liu and colleagues found that the crystal naturally splits into competing magnetic domains whose signals overlap and hide the underlying order. Stretching the material along one axis forced those domains to merge into a single orientation, letting the team resolve the magnetic structure and measure the Hall signal cleanly for the first time. Tuning the uniaxial strain then reversed the polarity of the Hall voltage while the main magnetic order stayed in place. The group calculates that roughly 1 percent strain produces a change comparable to a temperature swing of about 150 degrees, a comparison that matters because mechanical tuning is far easier to apply in a device than such a large thermal shift. The result appears in Physical Review X and treats strain as a practical handle on an altermagnetic electrical signature.[1]