Emergent magnetic and charge ordered phases in freestanding ultrathin \ce{LaVO3}

TL;DR

This study uses density functional theory to explore magnetic and charge phases in freestanding ultrathin LaVO3 films, revealing thickness-dependent magnetic transitions and doping-induced charge orderings.

Contribution

It provides the first detailed theoretical analysis of intrinsic properties and phase transitions in freestanding ultrathin LaVO3, highlighting effects of thickness and doping.

Findings

Sequence of magnetic phase transitions with thickness, from stripe-AFM to bulk-like C-AFM.

Charge transfer doping induces surface ferromagnetism and charge ordering patterns.

Hole doping drives ferromagnetic states and alters charge order periodicity.

Abstract

Transition metal oxide perovskites are an ideal platform for exploring the interplay between spin, orbital, charge and lattice degrees of freedom. Among them, \ce{LaVO3} has been extensively studied in heterostructures and superlattices, where exotic phases have been reported. Motivated by the advances in freestanding oxide membranes, we investigate the intrinsic properties of freestanding ultrathin \ce{LaVO3} films using density functional theory. Our calculations reveal a sequence of magnetic phase transitions with thickness, starting from stripe-AFM in monolayer until the bulk like C-AFM is recovered. Beyond four layers, polar catastrophe driven charge transfer dopes the surface layers giving rise to stripe-AFM and ferromagnetic surface states while the central layers remain bulk like. We further explore this fact by studying charge doped monolayer, discovering that hole doping drives the system into ferromagnetic state. Doping also induced charge ordering in the system. A striped charge ordering pattern is observed at 0.5 h/fu, while a 3:1 stripe pattern emerges at 0.25 h/fu, indicating that the periodicity of the superstructure changes with doping concentration.