Tip Induced Surface Defect migration and Conductivity Studies in Tetragonal, Rhombohedral and Mixed-Phase epitaxial BiFeO3 Thin Films

Saj Mohan, M M and M V, S and Ramadurai, Ranjit (2018) Tip Induced Surface Defect migration and Conductivity Studies in Tetragonal, Rhombohedral and Mixed-Phase epitaxial BiFeO3 Thin Films. MRS Advances. pp. 1-6. ISSN 2059-8521

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Abstract

BiFeO3 (BFO) is the most studied room temperature multiferroic compound. In this work we demonstrate a template assisted growth process through which the growth strain is controlled to achieve required phase of BFO. Growth of (∼20nm) fully strained tetragonal (T), rhombohedral (R) and mixed phase of T and R of Bismuth ferrite (BiFeO3) was achieved by varying the thickness of the template layer. The different phases were confirmed by using high resolution x-ray diffractions studies. The conductivity map of all the three phases were carried out using an atomic force microscope operating in conductive mode. Tip induced surface defect migration within a given grain was observed in pure phases and the conductivity map confirmed the same. The room temperature resistivity is found to be decreasing systematically from 1.1×106 Ωm , 935×105 Ωm and 1.16×104 Ωm respectively for tetragonal, mixed phase and rhombohedral phase BFO. In the case of mixed phase both the nano- scale and macroscopic leakage current studies show low conductivity, which could be due to the increased pinning sites that increases the energy barrier for the defect migration. The local nano-scale measurements and conductivity mapping corroborates well with the macroscopic studies.

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