Modulating Magnetism in Ferroelectric Polymer-Gated Perovskite Manganite Films with Moderate Gate Pulse Chains

Hon Fai Wong, Sheung Mei Ng, Wen Zhang, Yu Kuai Liu, Ping Kwan Johnny Wong, Chi Sin Tang, Ka Kin Lam, Xu Wen Zhao, Zhen Gong Meng, Lin Feng Fei, Wang Fai Cheng, Danny Von Nordheim, Wai Yeung Wong, Zong Rong Wang, Bernd Ploss, Ji Yan Dai, Chee Leung Mak, Andrew Thye Shen Wee, Chi Wah Leung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Most previous attempts on achieving electric-field manipulation of ferromagnetism in complex oxides, such as La0.66Sr0.33MnO3 (LSMO), are based on electrostatically induced charge carrier changes through high-k dielectrics or ferroelectrics. Here, the use of a ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene [P(VDF-TrFE)], as a gate dielectric to successfully modulate the ferromagnetism of the LSMO thin film in a field-effect device geometry is demonstrated. Specifically, through the application of low-voltage pulse chains inadequate to switch the electric dipoles of the copolymer, enhanced tunability of the oxide magnetic response is obtained, compared to that induced by ferroelectric polarization. Such observations have been attributed to electric field-induced oxygen vacancy accumulation/depletion in the LSMO layer upon the application of pulse chains, which is supported by surface-sensitive-characterization techniques, including X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. These techniques not only unveil the electrochemical nature of the mechanism but also establish a direct correlation between the oxygen vacancies created and subsequent changes to the valence states of Mn ions in LSMO. These demonstrations based on the pulsing strategy can be a viable route equally applicable to other functional oxides for the construction of electric field-controlled magnetic devices.

Original languageEnglish
Pages (from-to)56541-56548
Number of pages8
JournalACS Applied Materials and Interfaces
Volume12
Issue number50
DOIs
Publication statusPublished - 16 Dec 2020

Keywords

  • electric-field effect
  • LSMO
  • magnetism
  • oxygen vacancies
  • P(VDF-TrFE)

ASJC Scopus subject areas

  • Materials Science(all)

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