Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films


Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films

Shen, X.; Qiu, X.; Su, D.; Zhou, S.; Li, A.; Wu, D.

Transport characteristics of ultrathin SrRuO3 films, deposited epitaxially on TiO2-terminated SrTiO3 (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variable range hopping model, indicating a strongly localized state. Magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.

Keywords: SrRuO3; metal-insulator transition

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Publ.-Id: 21426