Detection and 180° Electrical Switching of Néel Vector in Altermagnets*

Altermagnet is an emerging magnetic phase with alternating spins and spin splitting band structure, thus combining the advantages of both antiferromagnets and ferromagnets [1-3]. However, as crucial components, the electrical detection and electrical 180^o switching of the Néel vector as well as the corresponding spin-splitting, are very challenging. We demonstrated that in altermagnets Mn₅Si₃ [4] and CrSb [5], the unique anomalous Hall effect can be adopted for electrical readout of opposite Néel vectors. A new mechanism was proposed for the electrical 180^o switching of the Néel vector via spin-orbit torques by designing asymmetric switching barriers and experimentally achieved it. Thus it is termed as barrier-asymmetric spin-orbit torque. It is made possible by the fixed chirality between Néel vector and tiny relativistic net moment due to the Dzyaloshinskii-Moriya interaction. Based on the novel readout and manipulation methods, we fabricated prototype memory devices that can accomplish robust write and read cycles. Furthermore, controllable Néel vector enables controllable spin-charge interconversion through altermagnetic and inverse altermagnetic spin splitting effect [2,3,6].