Modulated Spin Transport in Two-Dimensional (2D) Nanomagnet CrOBr under Strain Engineering*

Recent findings related to two-dimensional (2D) magnets demonstrate the capacity to manipulate and regulate both electronic and magnetic states at room temperature [1, 2, 3, 4]. In this study, we showcase controlled spin transport across different magnetic phases of the 2D semiconductor CrOBr [5] using first-principles density functional theory combined with the Non-Equilibrium Green’s function (NEGF) technique. Our findings reveal a noteworthy connection between its magnetic order and charge carriers. Firstly, we examine the spin-split electronic band structure of 2D - CrOBr under strain engineering. The outcomes reveal that the band structure of monolayer CrOBr displays distinct spin characteristics across various magneto-electric phases, attainable through the application of both uniaxial and biaxial strains. CrOBr exhibits versatile phase tunability, transitioning from a magnetic semiconductor state to half-metallic behavior and further to a magnetic metal, all achieved through strain variation. The transition from ferromagnetic (FM) to antiferromagnetic (AFM) state was also observed to occur with an increase in compressive strain of over -10% along the zigzag direction. In the biaxial strain scenario, the AFM state was found at strain levels of -14%, -16%, -18%, 8%, 10%, and 12%, respectively. Notably, a remarkable spin-filtering effect occurs, achieving a high spin injection efficiency of approximately 100% for transport along the armchair direction. Our research shows that CrOBr displays highly anisotropic transport behavior with perfect spin filtering, presenting new possibilities for strain-engineered magneto-electronic devices.