title: Understanding the magnetic interaction between intrinsic defects and impurity ions in room-temperature ferromagnetic Mg1-xFexO thin films.
abstract: Understanding the nature and characteristics of the intrinsic defects and impurities in the dielectric barrier separating the ferromagnetic electrodes in a magnetic tunneling junction is of great importance for understanding the often observed 'barrier-breakdown' therein. In this connection, we present herein systematic experimental (SQUID and synchrotron-radiation-based x-ray absorption spectroscopy) and computational studies on the electronic and magnetic properties of Mg1-xFexO thin films. Our studies reveal: (i) defect aggregates comprised of basic and trimer units (Fe impurity coupled to 1 or 2 Mg vacancies) and (ii) existence of two competing magnetic orders, defect- and dopant-induced, with spin densities aligning anti-parallel if the trimer is present in the oxide matrix. These findings open up new avenues for designing tunneling barriers with high endurance and tunneling effect upon tuning the concentration/distribution of the two magnetic orders.
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Center for Engineering Concepts Development, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.
authors.forename: Mukes
authors.initials: M
authors.lastname: Kapilashrami
authors.forename: Yung Jui
authors.initials: YJ
authors.lastname: Wang
authors.forename: Xin
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authors.lastname: Li
authors.forename: Per-Anders
authors.initials: PA
authors.lastname: Glans
authors.forename: Mei
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authors.lastname: Fang
authors.forename: Anastasia V
authors.initials: AV
authors.lastname: Riazanova
authors.forename: Lyubov M
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authors.lastname: Belova
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authors.lastname: Rao
authors.forename: Yi
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authors.lastname: Luo
authors.forename: Bernardo
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authors.lastname: Barbiellini
authors.forename: Hsin
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authors.lastname: Lin
authors.forename: Robert
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authors.lastname: Markiewicz
authors.forename: Arun
authors.initials: A
authors.lastname: Bansil
authors.forename: Zahid
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authors.lastname: Hussain
authors.forename: Jinghua
authors.initials: J
authors.lastname: Guo