Effect of picosecond strain pulses on thin layers of the ferromagnetic semiconductor (Ga,Mn)(As,P)

TL;DR

This study investigates how picosecond acoustic strain pulses influence the magnetic and optical properties of a thin (Ga,Mn)As:P layer, revealing strain-induced reflectivity changes independent of magnetization dynamics.

Contribution

It demonstrates that picosecond strain pulses cause measurable reflectivity variations in (Ga,Mn)As:P, modeled through interferometric measurements, distinguishing strain effects from magnetic responses.

Findings

Strain pulses induce transient MOKE signals with oscillations.

Reflectivity changes are accurately modeled by layer thickness variations.

Strain effects are separable from magnetization dynamics.

Abstract

The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of (Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect (MOKE). A transient MOKE signal followed by low amplitude oscillations was evidenced, with a strong dependence on applied magnetic field, temperature and ps-ASP amplitude. Careful interferometric measurement of the layer's thickness variation induced by the ps-ASP allowed us to model very accurately the resulting signal, and interpret it as the strain modulated reflectivity (differing for $\sigma_{\pm}$ probe polarizations), independently from dynamic magnetization effects.