Non-local spin valve in Van der Pauw cross geometry with four ferromagnetic electrodes

TL;DR

This paper explores a Van der Pauw cross geometry with four ferromagnetic electrodes for non-local spin valves, revealing large spin voltage increases, infinite GMR, switch effects, and potential for spin Hall effect probing and reprogrammable logic.

Contribution

It introduces a novel device geometry that enhances non-local spin signals and enables multiple functionalities like logic operations and spin Hall effect measurement.

Findings

Potentially large increase of non-local spin voltage

Infinite GMR for non-local resistance under symmetry conditions

Device functions as a reprogrammable magneto-logic gate

Abstract

We consider a non-local spin valve in a Van der Pauw cross geometry with four ferromagnetic electrodes. Two antiparallel ferromagnets are used as (charge) source and drain while the detector circuit involves measuring the voltage between two collinear ferromagnets with parallel or antiparallel magnetizations. We find a potentially large increase of the non-local spin voltage. The setup displays several additional interesting properties: (i) infinite GMR for the non-local resistance (if a symmetry requirement for the device is met); (ii) ON-OFF switch effect, when the injector electrodes are parallel instead of antiparallel; (iii) insensitivity to offset voltages. The device can additionally be used as a Direct Spin Hall Effect probe and as a reprogrammable magneto-logic gate implementing basic operations (NOR, NAND, inverter, AND, OR,...).