Spin switch and spin amplifier: magnetic bipolar transistor in the saturation regime

TL;DR

This paper demonstrates that magnetic bipolar transistors can amplify currents in the saturation regime, with their behavior influenced by spin orientations, enabling potential applications in spin detection and magnetic control of current.

Contribution

It introduces the concept that MBTs can operate as amplifiers in saturation mode, with current sign and gain controlled by spin orientations, a novel insight in spintronics.

Findings

Current amplification in saturation mode demonstrated

Collector current sign depends on spin orientation

Potential for spin-based electrical detection and switching

Abstract

It is shown that magnetic bipolar transistors (MBT) can amplify currents even in the saturation regime, in which both the emitter-base and collector-base junctions are forward biased. The collector current and the current gain can change sign as they depend on the relative orientation of the equilibrium spin in the base and on the nonequilibrium spin in the emitter and collector. The predicted phenomena should be useful for electrical detection of nonequilibrium spins in semiconductors, as well as for magnetic control of current amplification and for current switching.