Theoretical analysis of the inverse Edelstein effect at the LaAlO$_3$ / SrTiO$_3$ interface with an effective tight-binding model: Important role of the second $d_{xy}$ subband

TL;DR

This paper provides a theoretical analysis of the inverse Edelstein effect at the LaAlO$_3$ / SrTiO$_3$ interface, emphasizing the importance of the second $d_{xy}$ subband in spin-to-charge conversion efficiency.

Contribution

It introduces an effective tight-binding model that includes the second $d_{xy}$ subband to explain experimental temperature dependence of spin-to-charge conversion.

Findings

The second $d_{xy}$ subband significantly influences the conversion efficiency.

The model accurately reproduces experimental temperature dependence.

Quantization of multi-band structure is crucial for understanding the effect.

Abstract

The two-dimensional electron gas formed at interfaces between SrTiO$_3$ and other materials has attracted much attention since extremely efficient spin-to-charge current conversion has been recently observed at these interfaces. This has been attributed to their complicated quantized multi-orbital structures with a topological feature. However, there are few reports quantitatively comparing the conversion efficiency values between experiments and theoretical calculations at these interfaces. In this study, we theoretically explain the experimental temperature dependence of the spin-to-charge current conversion efficiency using an 8x8 effective tight-binding model considering the second $d_{xy}$ subband, revealing the vital role of the quantization of the multi-band structure.