Altermagnetism in MnTe: Origin, predicted manifestations, and routes to detwinning

MnTe has recently attracted attention as an altermagnetic candidate. Experimentally it has an altermagnetic order of ferromagnetic $ab$ planes, stacked antiferromagnetically along c. We show that this magnetic order (by itself nontrivial, since the in-plane exchange in antiferromagnetic) opens intriguing possibility of manufacturing altermagnetically detwinned samples and generate observable magneto-optical response (which we calculate from first principles) as a signature of altermagnetism.