Temperature and electric field dependence of spin relaxation in graphene on SrTiO$_3$

TL;DR

This study investigates how the substrate SrTiO$_3$ influences spin relaxation in graphene, revealing significant spin transport capabilities and the underlying mechanisms affecting spin lifetime and relaxation processes.

Contribution

It demonstrates the suitability of SrTiO$_3$ as a substrate for enhanced spin transport in graphene and analyzes the temperature and gate dependence of spin relaxation mechanisms.

Findings

Spin relaxation time up to 1.2 ns at 290 K

Spin relaxation length up to 5.6 μm at 290 K

Similar order of Elliott-Yafet and D'Yakonov-Perel' relaxation rates

Abstract

The theoretically predicted intrinsic spin relaxation time of up to 1 $\mu s$ in graphene along with extremely high mobilities makes it a promising material in spintronics. In spite of extensive experimental studies of spin relaxation and understanding of its precise mechanism, it is still unclear as to why the spin lifetime in graphene is three orders of magnitude below the theoretical predictions. Central to this discrepancy is the role of the local environment including that of the underlying substrate. In this work, we use the electronically rich platform SrTiO$_3$ and study its suitability in supporting spin transport in graphene. We find spin relaxation time and length as large as 1.2 $\pm$ 0.1 ns and 5.6 $\pm$ 0.5 $\mu m$ respectively at 290 K in graphene on SrTiO$_3$ using a non-local measurement scheme. We analyze the temperature variation of the spin transport parameters in graphene and attribute the temperature dependence of the spin transport parameters in graphene to spin orbit coupling or structural phase transition in SrTiO$_3$. Furthermore, from the gate dependence of the spin transport parameters, the relation between spin relaxation time and momentum relaxation time is extracted; the Elliot-Yaffet and D'Yakonov-Perel' spin relaxation rates are found to be of similar order.