Confined polaronic transport in (LaFeO3)n/(SrFeO3)1 superlattices

Seo Hyoung Chang,Anand Bhattacharya,Albina Y Borisevich,Jeffrey A Eastman,Dillon D Fong,Young-Min Kim,Seong Keun Kim,Woo Seok Choi,Da Woon Jeong,Yongqi Dong,Chad M Folkman

doi:10.1063/1.5110190

Abstract

Functional oxide superlattices offer new and exciting possibilities for the exploration of emergent properties at the nanoscale. While the behavior of La1−xSrxFeO3 films has been extensively investigated at low temperatures, few studies have been carried out at high temperatures, particularly for LaFeO3/SrFeO3 superlattice systems. Here, we investigate the transport behavior and optical properties of (LaFeO3)n/(SrFeO3)1 superlattices at 373 K and above. Using optical spectroscopy, we observe a low energy excitation at ∼1 eV, attributable to charge transfer between the O 2p and Fe 3d states of the δ-doped single SrFeO3 layer. From in-plane conductivity measurements on the superlattices, we determine activation energies that are much lower than those of alloyed samples and vary with the total number of SrFeO3 layers. This suggests that polaronic transport is confined near the SrFeO3 regions, permitting mobilities significantly enhanced over those in alloyed thin films.

Highlights

La1−xSrxFeO3 (LSFO) is a strongly correlated oxide known to display a variety of unique material properties
Researchers can directly examine the fundamental mechanisms governing transport at these elevated temperatures, utilizing model systems and state-of-the-art characterization probes to help distinguish between the effects of microstructure and intrinsic/extrinsic contributors to electrical conduction
Such atomically controlled, layered structures allow the study of cation ordering effects on electronic behavior,16–19 a topic of increasing interest in materials design20–22 and the one that may lead to the development of novel materials for energy

Summary

Introduction

La1−xSrxFeO3 (LSFO) is a strongly correlated oxide known to display a variety of unique material properties. Folkman,1 Da Woon Jeong,7 Woo Seok Choi,8 Albina Y.

Results

Conclusion