Interface Engineered Room-Temperature Ferromagnetic Insulating State in Ultrathin Manganite Films

Weiwei Li; Bonan Zhu; Qian He; Albina Y Borisevich; Chao Yun; Rui Wu; Ping Lu; Zhimin Qi; Qiang Wang; Aiping Chen; Haiyan Wang; Stuart A Cavill; Kelvin H L Zhang; Judith L MacManus-Driscoll

doi:10.1002/advs.201901606

Interface Engineered Room-Temperature Ferromagnetic Insulating State in Ultrathin Manganite Films

Adv Sci (Weinh). 2019 Nov 11;7(1):1901606. doi: 10.1002/advs.201901606. eCollection 2020 Jan.

Authors

Weiwei Li¹, Bonan Zhu¹, Qian He², Albina Y Borisevich³, Chao Yun¹, Rui Wu¹, Ping Lu⁴, Zhimin Qi⁵, Qiang Wang⁶, Aiping Chen⁷, Haiyan Wang⁵, Stuart A Cavill^{8

9}, Kelvin H L Zhang¹⁰, Judith L MacManus-Driscoll¹

Affiliations

¹ Department of Materials Science and Metallurgy University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK.
² Cardiff Catalysis Institute School of Chemistry Cardiff University Main Building, Park Place Cardiff CF10 3AT UK.
³ Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA.
⁴ Sandia National Laboratory Albuquerque NM 87185 USA.
⁵ School of Materials Engineering Purdue University West Lafayette IN 47907 USA.
⁶ Department of Physics and Astronomy West Virginia University Morgantown WV 26506 USA.
⁷ Center for Integrated Nanotechnologies Los Alamos National Laboratory Los Alamos NM 87545 USA.
⁸ Department of Physics University of York York YO10 5DD UK.
⁹ Diamond Light Source Didcot OX11 0DE UK.
¹⁰ State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China.

Abstract

Ultrathin epitaxial films of ferromagnetic insulators (FMIs) with Curie temperatures near room temperature are critically needed for use in dissipationless quantum computation and spintronic devices. However, such materials are extremely rare. Here, a room-temperature FMI is achieved in ultrathin La_0.9Ba_0.1MnO₃ films grown on SrTiO₃ substrates via an interface proximity effect. Detailed scanning transmission electron microscopy images clearly demonstrate that MnO₆ octahedral rotations in La_0.9Ba_0.1MnO₃ close to the interface are strongly suppressed. As determined from in situ X-ray photoemission spectroscopy, O K-edge X-ray absorption spectroscopy, and density functional theory, the realization of the FMI state arises from a reduction of Mn e_g bandwidth caused by the quenched MnO₆ octahedral rotations. The emerging FMI state in La_0.9Ba_0.1MnO₃ together with necessary coherent interface achieved with the perovskite substrate gives very high potential for future high performance electronic devices.

Keywords: ABO3 perovskite oxides; ferromagnetic insulators; interface engineering; manganite thin films; octahedral proximity effect.