Spin-dependent transport and spin transfer torque in a borophene-based spin valve

Abstract

This article presents a theoretical analysis of spin-dependent transport and spin-transfer torque in a borophene-based ferromagnetic/normal/ferromagnetic junction. This study focuses on borophene nanoribbons (BNRs) as a basis for spin valve numerical calculations for the investigation of conduction in both configurations where the magnetization vectors of the leads are parallel or antiparallel to each other (P and AP configurations, respectively), magnetoresistance (MR), and spin transfer torque (STT). The Landauer formalism and non-equilibrium Green's function (NEGF) approaches are used to derive the spin-dependent tunneling currents in the Magnetic Tunnel Junction (MTJ). The results of the calculations for a zigzag BNR show that the conductance is always larger than e²/h for the P configuration of lead magnetizations. For the AP configuration, the conductance becomes zero in specific energy ranges. A perfect MR plateau is found for the junction in the absence of disorder, which proves to be an excellent spin valve candidate. The variations of STT with Fermi energy and the relative angle between the magnetizations of two electrodes are studied for different strengths of ferromagnetic magnetization. The STT per unit bias voltage, as a function of Fermi energy, decreases significantly near the Dirac point energy. A sinusoidal oscillatory pattern can be evidently observed in the STT at unit bias voltage V versus the angle between the magnetizations of two electrodes, which amplifies as M increases. Borophene has unique properties, including low density and high hardness, heat resistance, and electrical conductance, which make it a promising candidate for spintronics. This article provides a comprehensive analysis of the spin-dependent properties of borophene and its potential applications in spintronics.