Spin-polarized quantum capacitance in 8- <i>Pmmn</i> monolayer borophene

Abstract

We investigate the spin-resolved quantum capacitance in 8-Pmmn monolayer borophene, a two-dimensional Dirac material distinguished by its anisotropic and tilted Dirac cone dispersion. Our findings reveal that spin polarization, temperature, tilt in the Dirac cone, external electric fields, and intrinsic spin–orbit interaction collectively tune its quantum capacitance. In particular, spin-up and spin-down states exhibit distinct capacitance, with spin-up channels displaying quantum capacitance with narrower gap widths than spin-down channels due to the interplay between spin–orbit interaction and transverse electric fields. The tilt in the Dirac cone enhances the density of states near the Fermi level, leading to a substantial increase in the quantum capacitance, while elevated temperatures suppress it through thermal broadening of electronic states. These results reveal the highly tunable electrostatic response of 8-Pmmn borophene and indicate its promise for spintronic and nanoscale electronic applications.