A gate-induced switch in zigzag graphene nanoribbons and charging effects

Spin-selective response tunability in two-dimensional nanomagnet

Recent reports on the two-dimensional (2D) material CrOCl revealed magnetic ordering and spin polarisation with Curie TemperatureTc∼ 160 K, values higher than most diluted magnetic semiconductors. Here, we investigate the uniaxial and biaxial strain-dependent electronic and transport properties of CrOCl monolayer using first-principles based calculations. The calculated Young's modulus indicates high mechanical flexibility for the application of high strain. Our study shows that strain can induce phase changes from a bipolar magnetic semiconductor → half metal → magnetic metal in the material, leading to interesting spin-resolved conductance with 100% spin filtering. Furthermore, the current-voltage (I-V) response showed conductance fluctuations, characterised by peak to valley ratio and switching efficiency offering high strain assisted tunability. Overall, CrOCl shows a highly anisotropic behaviour with the material displaying 100% spin polarisation in the tensile strain region. The electronic, transport and mechanical properties indicate that CrOCl is a versatile 2D material with multi-phase capabilities having promising applications for future nanospintronic devices.

Wave Function Parity Loss Used to Mitigate Thermal Broadening in Spin-orbit Coupled Zigzag Graphene Analogues

Carrier transport through a graphene zigzag nanoribbon (ZNR) is possible to be blocked by a p-n profile implemented along its transport direction. However, we found that in cases of analogous materials with significant intrinsic spin-orbit coupling (SOC), i.e. silicene and germanene, such a profile on ZNR of these materials allows transmission mostly through spin-orbit coupled energy window due to the loss of the parity of wave functions at different energies caused by SOC. Next, a p-i-n scheme on germanene ZNR is proposed to simultaneously permit edge transmission and decimate bulk transmission. The transmission spectrum is shown to mitigate the effect of thermal broadening on germanene and silicene ZNR based spin-separators by improving spin polarization yield by 400% and 785%, respectively, at 300 K. The importance of proper gate voltage and position for such performance is further elucidated. Finally, the modulation the current output of the proposed U-shape p-i-n device while maintaining its spin polarization is discussed.