Promoted current-induced spin polarization in inversion symmetry broken topological insulator thin films

TL;DR

This paper provides a theoretical analysis of how disorder, hybridization, and inversion symmetry breaking influence current-induced spin polarization in topological insulator thin films, highlighting conditions that enhance spin responses for spintronic applications.

Contribution

It introduces a comprehensive theoretical framework incorporating vertex corrections to analyze spin polarization in disordered topological insulator thin films with broken inversion symmetry.

Findings

Spin susceptibility is nonzero around a finite zero-gap range.

Increased hybridization causes asymmetry in spin response.

Enhanced potential difference significantly boosts spin polarization.

Abstract

We theoretically investigate current-induced spin polarization in disordered topological insulator thin films with broken inversion symmetry under an applied in-plane electric field. Utilizing the Kubo formalism within the self-consistent Born approximation and incorporating vertex corrections to account for multiple scattering events, we analyze how disorder, chemical potential, the electrostatic potential difference between the top and bottom surfaces, and momentum-dependent hybridization affect the spin susceptibility. Our results reveal that the spin susceptibility exhibits nonzero values within a finite range around a zero gap, and this range broadens as the chemical potential increases. A higher hybridization strength induces asymmetry in the spin response. A stronger potential difference, breaking inversion symmetry, significantly enhances polarization. This enhancement is a trend attributable to band inversion and is further refined by vertex corrections. These findings provide a theoretical framework for tuning spin-charge conversion in topological thin films, with implications for spintronic device applications.