Unraveling how electronic and spin structures control macroscopic properties of manganite ultra-thin films

Xinmao Yin,Andrivo Rusydi,Junling Wang,Daniel Schmidt,Peng Ren,Xiao Chi,Lu You,Xiaojiang Yu,Mark B H Breese,Caozheng Diao,Natalia Palina,Baomin Wang,Ping Yang,Muhammad Aziz Majidi

doi:10.1038/am.2015.65

Abstract

The interplay between hybridization, orbital occupancy and spin governs the transport and magnetic properties of ultrathin manganites. This finding was made by scientists in Singapore, China and Indonesia based on a new analysis of a doped manganite ultrathin film. Thin films of doped perovskite manganites exhibit exotic properties, but it is unclear what roles the spin, charge and orbital degrees of freedom of these strongly correlated electron systems play in generating such properties. Andrivo Rusydi, Junling Wang and collaborators observed an insulating, ferromagnetic phase below 140 kelvin, an insulating, paramagnetic phase above 195 kelvin, and a metal-like state at intermediate temperatures in their film. They found that the O2p–Mn3d hybridization strength drops with temperature, making the system more insulating and ferromagnetic, whereas the Jahn-Teller effect decreases dramatically in the intermediate temperature range, making the system more metal-like.

Highlights

Using a combination of temperature-dependent spectroscopic ellipsometry, X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) both at O K-edge and Mn L3,2-edges as well as transport measurements, we show for the first time how the interplay of hybridization, orbital occupancy and spin controls the macroscopic properties
To further demonstrate how our comprehensive methodology works, we present a study on LSMO ultra-thin films on SrTiO3 substrates (LSMO/STO) for comparison
To reveal the microscopic mechanism behind these transitions, we use a combination of techniques including temperature-dependent spectroscopic ellipsometry, XAS and XMCD to probe the detailed electronic and spin structures directly

Summary

Introduction

Perovskite manganites exhibit fascinating transport and magnetic properties, essential for fundamental research and applications.[1,2,3,4,5,6,7] In particular, with the development of thin film nanoscale technologies, more exotic properties have been observed in doped-manganite thin films over a wide range of temperature.[8,9,10,11,12,13,14,15,16,17,18,19,20,21] the origin of many fundamental phenomena remains unclear. The temperature-dependent O2p-Mn3d hybridization strength, the energy splitting of eg by the Jahn–Teller effect and its band width are extracted. From these we propose the temperature-dependent density of states of the system

Methods

Results

Conclusion