Tunneling magnetoresistance and thermoelectric effect in magnetic Fibonacci phosphorene superlattices

Abstract

The efficiency of energy conversion through the thermoelectric effect has increased significantly due to recent advances in nanostructuring techniques as well as potential use of low-dimensional materials. In this work, we theoretically study the electronic transport, thermoelectric effect and tunnel magnetoresistance (TMR) in a phosphorene monolayer modulated by aperiodic superlattices (SLs) of magnetic fields in both parallel (P) and antiparallel (AP) configurations of the ferromagnetic strips. From the two-band tight-binding model of phosphorene, we have calculated the transport and thermoelectric properties in the Landauer–Büttiker formalism. We found enhanced thermoelectric properties of Fibonacci SLs in AP configuration, obtaining maximum values of the Sebeeck coefficient, power factor and figure of Merit of S=0.66 mVK −1, PF = 5.32 pWK −2 and ZT=65.14, respectively, which are higher than periodic SLs. It should be emphasized that the highest ZT peak represents an idealized electronic-only estimate bound. Also, we calculate the power-efficiency ( PMax−η) trade-off curves. We found relevant optimized regions with extreme points 45.90 pW−0.34 and 54.83 pW−0.30 for Fibonacci SL in P configuration, and the region between 20.13 pW−0.45 and 49.87 pW−0.34 in AP configuration, which means that increasing the power factor (PF) implies reducing efficiency and vice versa. In short, low-dimensional thermoelectricity could be improved under magnetic effects. Finally, Fibonacci-type SL exhibits a better TMR than periodic SL, which behaves as a conductor for P configuration and as an insulator for AP configuration. Therefore, magnetic aperiodic SLs could be used in magnetoresistive devices.