Distortion-Driven Carrier Decoupling in Doped LiMgPO4

TL;DR

This paper uncovers how lattice distortions in doped LiMgPO4 cause electrons to localize as small polarons while holes remain mobile, explaining enhanced energy storage properties.

Contribution

It reveals a microscopic mechanism of carrier decoupling driven by lattice distortions, advancing understanding of polaron behavior in complex oxides.

Findings

Electrons form stable small polarons trapped by dopant-induced potential.

Holes form delocalized polarons that migrate efficiently.

The decoupling of electron and hole dynamics explains improved energy storage.

Abstract

The interplay between lattice distortions and charge carriers governs the properties of many functional oxides. In alkali-doped LiMgPO4, a significant enhancement in dosimetric response is observed, but its microscopic origin is not understood. Using non-adiabatic molecular dynamics, we reveal a fundamental mechanism of carrier decoupling driven by a hierarchy of lattice distortions. We show that electrons localize into stable small polarons on an ultrafast timescale, trapped by the strong local potential induced by the dopant, while holes form more delocalized polarons that migrate efficiently through a lattice smoothed by global strain. The stark contrast between the dynamics of trapped electrons and mobile holes explains the suppressed recombination and enhanced energy storage. These results present a clear physical picture of how multiscale lattice distortions can independently control electron and hole transport, offering new insights into the physics of polarons in complex materials.