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Article Dans Une Revue Physical Review Materials Année : 2021

Surface and bulk ferroelectric phase transition in super-tetragonal BiFeO 3 thin films

Alexandre Gloter

Résumé

The temperature-dependent ferroelectric properties of super-tetragonal BiFeO3 are investigated using surface-sensitive low-energy electron microscopy (LEEM). We use epitaxial oxide BiFeO3/Ca0.96Ce0.04MnO3 bilayers grown by pulsed laser deposition on YAlO3 substrates. Ferroelectric, micrometer-scale domains are written by piezoresponse force microscopy and subsequently observed by LEEM from room temperature up to about 950 K. Kelvin probe force microscopy and LEEM spectroscopy reveal that the surface potential is efficiently (>50%) screened by adsorbates that are only released after annealing above 873 +/- 50 K in ultrahigh vacuum. The surface structure and chemistry of the ferroelectric thin films are analyzed using scanning transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoelectron spectroscopy, discarding the occurrence of a putative "skin layer" effect. While its magnetic and structural transitions were reported in the literature, the true, ferroelectric Curie temperature of super-tetragonal BiFeO3 has not been determined so far. Here, we measure a Curie temperature of 930 +/- 30 K for the super-tetragonal BiFeO3 surface and corroborate it with volume-sensitive, temperature-dependent x-ray diffraction measurements. These results suggest that LEEM can be used as a powerful tool to probe surface charge and ferroelectric transitions in ultrathin films.

Dates et versions

cea-04345118 , version 1 (14-12-2023)

Identifiants

Citer

Myriam Lachheb, Qiuxiang Zhu, Stéphane Fusil, Qiang Wu, Cécile Carrétéro, et al.. Surface and bulk ferroelectric phase transition in super-tetragonal BiFeO 3 thin films. Physical Review Materials, 2021, 5 (2), pp.024410. ⟨10.1103/PhysRevMaterials.5.024410⟩. ⟨cea-04345118⟩
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