Altermagnetism in Mn2SeX (X = O, S, Te) for magnetic tunnel junctions

Altermagnets uniquely combine compensated magnetic moments with broken PT symmetry, offering ferromagnet-like spin polarization alongside antiferromagnetic stability and ultrafast dynamics. Leveraging these assets, AM-based devices hold immense promise for magnetic tunnel junctions, Hall sensors, and magnetocaloric applications. Guided by spin space group theory, we break the PT symmetry of MnSe via atomic substitution, yielding d-wave altermagnetic Mn2SeX (X = O, S, Te) with favorable spin electronic properties. Our analysis reveals that the rotational symmetry introduced by partial Se substitution serves as the microscopic origin of the non-relativistic spin splitting. Leveraging these superior spin transport characteristics, we demonstrate a tunneling magnetoresistance ratio of 376.3% in Mn2SeTe-based AMTJs. Our work not only establishes a theoretical paradigm for designing novel altermagnets but also computationally demonstrates their substantial potential for high-performance MTJ applications.