Polarization Dependent Optical Control of Atomic Arrangement in Multilayer Ge-Sb-Te Phase Change Materials

TL;DR

This study demonstrates polarization-dependent optical control of atomic arrangements in multilayer Ge-Sb-Te phase change materials, revealing how femtosecond laser pulses can induce reversible or irreversible structural changes.

Contribution

It introduces a method to manipulate atomic structures in phase change materials using polarized femtosecond laser pulses, highlighting the role of bond dissociation along specific crystallographic axes.

Findings

p-polarization more effectively induces atomic rearrangement

Reversible or irreversible structural changes depend on pump fluence

Ge-Te bond dissociation drives atomic rearrangement

Abstract

We report the optical perturbation of atomic arrangement in the layered GeTe/Sb_{2}Te_{3} phase change memory material. To observe the structural change, the coherent A_{1} mode of GeTe_{4} local structure is investigated at various polarization angles of femtosecond pump pulses with the fluence at < 78 \mu J/cm^{2}. p-polarization found to be more effective in inducing the A_{1} frequency shift that can be either reversible or irreversible, depending on the pump fluence. The predominant origin of this shift is attributed to rearrangement of Ge atoms driven by anisotropic dissociation of the Ge-Te bonds along the [111] axis after the p-polarized pulse irradiation.