Anisotropic magnetoresistance across Verwey transition in charge ordered Fe3O4 epitaxial films

Article

关键词: MAGNETOOPTICAL KERR SPECTROSCOPY;    LOW-TEMPERATURES;    MAGNETITE FILMS;    THIN-FILMS;    CONDUCTIVITY;    FERRITES;    LAYERS;    POINT;    RAMAN;    GAP;   

DOI  :  10.1103/PhysRevB.96.214434

来源: SCIE

【 摘 要 】

The anisotropic magnetoresistance (AMR) near the Verwey temperature (T-V) is investigated in charge ordered Fe3O4 epitaxial films. When the temperature continuously decreases below T-V, the symmetry of AMR in Fe3O4(100) film evolves from twofold to fourfold at a magnetic field of 50 kOe, where the magnetic field is parallel to the film surface, whereas AMR in Fe3O4(111) film maintains twofold symmetry. By analyzing AMR below T-V, it is found that the Verwey transition contains two steps, including a fast charge ordering process and a continuous formation process of trimeron, which is comfirmed by the temperature-dependent Raman spectra. Just below T-V, the twofold AMR in Fe3O4(100) film originates from uniaxial magnetic anisotropy. The fourfold AMR at a lower temperature can be ascribed to the in-plane trimerons. By comparing the AMR in the films with two orientations, it is found that the trimeron shows a smaller resistivity in a parallel magnetic field. The field-dependent AMR results show that the trimeron-sensitive field has a minimum threshold of about 2 kOe.

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