No abstract

Magnetic silicene superlattices (MSSLs) are versatile structures with spin-valley polarization and tunneling magnetoresistance (TMR) capabilities. However, the oscillating transport properties related to the superlattice periodicity impede stable spin-valley polarization states reachable by reversing the magnetization direction. Here, we show that aperiodicity can be used to improve the spin-valley polarization and TMR by reducing the characteristic conductance oscillations of periodic MSSLs (P-MSSLs). Using the Landauer-Büttiker formalism and the transfer matrix method, we investigate the spin-valley polarization and the TMR of Fibonacci (F-) and Thue-Morse (TM-) MSSLs as typical aperiodic superlattices. Our findings indicate that aperiodic superlattices with higher disorder provide better spin-valley polarization and TMR values. In particular, TM-MSSLs reduce considerably the conductance oscillations giving rise to two well-defined spin-valley polarization states and a better TMR than F- and P-MSSLs. F-MSSLs also improve the spin-valley polarization and TMR, however they depend strongly on the parity of the superlattice generation.

Magnetic silicene junctions are versatile structures with spin-valley polarization and magnetoresistive capabilities. Here, we investigate the temperature effects on the transport properties of single magnetic silicene junctions. We use the transfer matrix method and the Landauer-Büttiker formalism to calculate the transmittance, conductance, spin-valley polarization and tunneling magnetoresistance. We studied the case for T = 0 K, finding the specific parameters where the spin-valley polarization and the tunneling magnetoresistance reach optimized values. Regarding the temperature effects, we find that its impact is not the same on the different transport properties. In the case of the conductance, depending on the spin-valley configuration the resonant peaks disappear at different temperatures. The spin polarization persists at a considerable value up to T=80 K, contrary to the valley polarization which is more susceptible to the temperature effects. In addition, a stepwise spin-valley polarization can be achieved at low temperature. The tunneling magnetoresistance is attenuated considerably as the temperature rises, decreasing more than two orders of magnitude after T=20 K. These findings indicate that in order to preserve the spin-valley polarization and magnetoresistive capabilities of magnetic silicene junctions is fundamental to modulate the temperature adequately.