Spin-dependent transport in altermagnet CrSb-based magnetic tunnel junction

Altermagnetism, an emerging magnetic order state that combines the spin polarization of ferromagnets with the antiferromagnetic resistance to magnetic perturbations, provides a new route to overcome the performance bottleneck of traditional spintronic devices. This Letter focuses on the altermagnetic material CrSb, revealing the spin-polarized band structure protected by real space rotation and mirror operations in the three-dimensional Brillouin zone of CrSb through symmetry analysis and density functional theory calculations, as well as the role of spin–orbit coupling in regulating the degeneracy of the bands. Further, by combining the non-equilibrium Green's function method, we examine the quantum transport properties of altermagnetic CrSb-based magnetic tunnel junction (MTJ). Our results show that the tunneling magnetoresistance (TMR) near the Fermi level reaches 60% for a vacuum barrier of 2.196 Å. When the vacuum is replaced by an h-BN monolayer whose effective thickness is 4.4 Å, the TMR decreases to 20%, breaking the limitation of spin-polarized current dependence in traditional ferromagnetic MTJs. The research combined “Néel spin current” and clarified the cooperative transport mechanism of the spin channels of the altermagnetic sublattices. It not only broadens the theoretical framework of altermagnetic materials but also lays an important foundation for the design of spintronic devices based on g-wave symmetry altermagnetism.