All-optical four-state magnetization reversal in (Ga,Mn)As ferromagnetic semiconductors

TL;DR

This paper predicts all-optical control of four magnetic states in (Ga,Mn)As semiconductors using femtosecond laser pulses, enabling rapid and non-thermal magnetization switching through nonlinear optical effects.

Contribution

It introduces a theoretical model demonstrating four-state magnetization switching in ferromagnetic semiconductors driven by ultrafast optical pulses.

Findings

Switching occurs within 100 fs of excitation.

Magnetization reversal completes in approximately 100 ps.

Switching is controlled by coherent femtosecond photoexcitation.

Abstract

Using density matrix equations of motion and a tight-binding band calculation, we predict all-optical switching between four metastable magnetic states of (III,Mn)As ferromagnets. This switching is initiated non-thermally within 100fs, during nonlinear coherent photoexcitation. For a single optical pulse, magnetization reversal is completed after $\sim$100 ps and controlled by the coherent femtosecond photoexcitation. Our predicted switching comes from magnetic nonlinearities triggered by a femtosecond magnetization tilt that is sensitive to un--adiabatic light--induced spin interactions.