Ambipolar ferromagnetism by electrostatic doping of a manganite

• Published in: Nature communications Vol. 9; no. 1; pp. 1897 - 7
• Main Authors: Zheng, L. M., Wang, X. Renshaw, Lü, W. M., Li, C. J., Paudel, T. R., Liu, Z. Q., Huang, Z., Zeng, S. W., Han, Kun, Chen, Z. H., Qiu, X. P., Li, M. S., Yang, Shize, Yang, B., Chisholm, Matthew F., Martin, L. W., Pennycook, S. J., Tsymbal, E. Y., Coey, J. M. D., Cao, W. W.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.05.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/995; 639/301/119/997; 639/766/119/2793; Antiferromagnetism; Asymmetry; Colossal magnetoresistance; Density functional theory; Doping; Electrons; Ferromagnetic materials; Humanities and Social Sciences; Ionic liquids; Lanthanum compounds; Magnetism; Magnetoresistance; Magnetoresistivity; MATERIALS SCIENCE; multidisciplinary; Physical properties; Polarity; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-04233-5

Complex-oxide materials exhibit physical properties that involve the interplay of charge and spin degrees of freedom. However, an ambipolar oxide that is able to exhibit both electron-doped and hole-doped ferromagnetism in the same material has proved elusive. Here we report ambipolar ferromagnetism in LaMnO 3 , with electron–hole asymmetry of the ferromagnetic order. Starting from an undoped atomically thin LaMnO 3 film, we electrostatically dope the material with electrons or holes according to the polarity of a voltage applied across an ionic liquid gate. Magnetotransport characterization reveals that an increase of either electron-doping or hole-doping induced ferromagnetic order in this antiferromagnetic compound, and leads to an insulator-to-metal transition with colossal magnetoresistance showing electron–hole asymmetry. These findings are supported by density functional theory calculations, showing that strengthening of the inter-plane ferromagnetic exchange interaction is the origin of the ambipolar ferromagnetism. The result raises the prospect of exploiting ambipolar magnetic functionality in strongly correlated electron systems. An ambipolar ferromagnet with both electron- and hole-doped ferromagnetism in a single material would facilitate understanding of ferromagnetic semiconductors for spintronic applications. Here the authors demonstrate ambipolar ferromagnetism in LaMnO 3 , using ionic liquid gating enabled electrostatic doping to produce electron–hole asymmetry.