Infinite magneto-resistance and bipolar effect in spin valves driven by spin batteries

TL;DR

This paper demonstrates that spin valves can exhibit an infinite magneto-resistance effect driven by pure spin currents, revealing a novel bipolar effect related to Johnson transistors, with potential for very large resistance ratios.

Contribution

It introduces the concept of infinite magneto-resistance in spin valves driven by spin batteries and links it to the bipolar effect, expanding understanding of spintronic device behavior.

Findings

Pure spin currents can induce infinite magneto-resistance in symmetric spin valves.

The effect is related to the bipolar effect of Johnson transistors.

Achievable magneto-resistance ratios can be extremely large in certain setups.

Abstract

It is shown that spin valves under suitable symmetry conditions exhibit an ON-OFF response to a spin battery. While a spin valve driven by a charge battery displays the usual GMR (Giant Magneto-Resistance), a pure spin current or pure spin accumulation can generate an infinite magneto-resistance effect(IMR). In practice the effect is curtailed by asymmetry but the achievable magneto-resistance ratio is still predicted to be unusually large in several example setups. It is closely related to the bipolar effect (BE) of Johnson transistor which can be triggered under the same symmetry conditions.