# Mesoscopic Interference of Rotated Spins in Graphene Coupled to High-Spin–Orbit-Coupling Substrates

## TL;DR

This paper studies how spin rotation in graphene changes when it is placed near materials with strong spin-orbit coupling, revealing unpredictable patterns in spin interference.

## Contribution

The study reveals the nonself-averaged, stochastic nature of spin interference in graphene with high-spin-orbit-coupling substrates.

## Key findings

- Spin rotation in graphene manifests as a zero-bias peak in differential conductance at low temperatures.
- The zero-bias peak is suppressed by small magnetic fields and varies stochastically with gate voltage.
- Both ferromagnetic Co and diamagnetic WSe2 substrates show similar mesoscopic behavior in spin interference.

## Abstract

We explore the manifestations of spin rotation in graphene
in proximity
with two different types of high-spin–orbit-coupling (SOC)
materials (ferromagnetic Co and nominally diamagnetic WSe2). Using weak antilocalization (WAL) as a probe of the induced rotation,
we demonstrate that spin interference exhibits a highly stochastic
(nonself-averaging) character in the mesoscopic limit. At low temperatures
(<20 K), the spin rotation is manifested as a zero-bias peak (or
zero-bias anomaly, ZBA) in the differential conductance, a feature
that, as expected for WAL, is suppressed by fairly modest magnetic
fields (<∼102 mT). The ZBA moreover exhibits
a stochastic variation when a gate voltage is used to sweep the Fermi
level through the graphene bands, with ranges for which the antilocalization
is either prominent or strongly suppressed. This mesoscopic character
is exhibited by both of the studied systems, whose ZBA is also damped
in similar fashion with increasing temperature. We thus provide fundamental
insight into the nonensemble-averaged (nonself-averaged) character
of spin interference in mesoscopic systems with strong SOC and, more
specifically, into how the details of spin rotation are impacted by
external gating. This understanding may ultimately enable the efficient
modulation of spin currents in future spintronic devices.