Giant doping response of magnetic anisotropy in MnTe

The authors show that minuscule amounts of Li suffice to tune antiferromagnetic MnTe from an easy-plane to easy-axis material. Upon heating towards the N\'eel temperature of 307 K, the spins do not gradually rotate back to a planar orientation, and instead maintain their axial orientation up to a relatively high temperature of 260 K, before quickly switching back to a planar orientation and crossing into the paramagnetic phase. Calculations indicate MnTe bears two competing magnetic ground states which can be manipulated by slightly shifting the Fermi level via Li-doping. Easy manipulation of the spins in MnTe could have significant implications for future spintronic devices and materials.