The origin of the dead-layer at the La0.67Sr0.33MnO3/SrTiO3 interface and dead-layer reduction via interfacial engineering

TL;DR

This study investigates the origin of dead-layer phenomena at La0.67Sr0.33MnO3/SrTiO3 interfaces, revealing oxygen vacancies caused by interfacial electric fields as a key factor, and demonstrates dead-layer reduction through atomic-level doping engineering.

Contribution

It provides a detailed understanding of dead-layer origins in oxide heterostructures and introduces a method to reduce dead-layer effects via interfacial doping strategies.

Findings

Dead-layer caused by hole depletion due to oxygen vacancies.

Oxygen vacancies are influenced by interfacial electric dipolar fields.

Doping-engineering reduces dead-layer by increasing interfacial hole concentration.

Abstract

Transition metal oxide hetero-structure has great potential for multifunctional devices. However, the degraded physical properties at interface, known as dead-layer behavior, present a main obstacle for device applications. Here we present the systematic study of the dead-layer behavior in La0.67Sr0.33MnO3 thin film grown on SrTiO3 substrate with ozone assisted molecular beam epitaxy. We found that the evolution of electric and magnetic properties as a function of thickness shows a remarkable resemblance to the phase diagram as a function of doping for bulk materials, providing compelling evidences of the hole depletion in near interface layers that causes dead-layer. Detailed electronic and surface structure studies indicate that the hole depletion is due to the intrinsic oxygen vacancy formation. Furthermore, we show that oxygen vacancies are partly caused by interfacial electric dipolar field, and thus by doping-engineering at the single-atomic-layer level, we demonstrate the dead-layer reduction in films with higher interfacial hole concentration.