Size-Dependent Magnetic, Transport, and Electronic Properties of Multiferroic BiFeO3 and Their Relevance to Smart and Sustainable Technologies.

• Grant number: 25/22048-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Diego Muraca
• Grantee: Henrique de Sordi
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 24/00998-6 - Center for Research and Innovation on Smart and Quantum Materials (CRISQuaM), AP.CEPID

Abstract

BiFeO3 (BFO) is one of the few room-temperature multiferroic materials, exhibiting the coexistence of ferroelectricity and antiferromagnetism. Its properties are strongly influenced by structural parameters, particularly crystalline size and the modulation of its spin cycloid ( 62-64 nm in bulk). This project aims to investigate how reducing crystalline size to the nanoscale and modifying the spin cycloid length impacts the magnetic, transport, and electronic behavior of BFO. Bulk BFO displays G-type antiferromagnetism with a superimposed long-period cycloid, suppressing macroscopic magnetization. Reducing crystal size below the cycloid length can disrupt this modulation, enhancing weak ferromagnetism. BFO has a direct band gap of 2.6-2.8 eV, relevant for optoelectronics and photovoltaics. Strain, size effects, and defects can tailor band gapvalues. Electric conduction is typically limited by oxygen vacancies and polaron hopping. Grain size reduction influences carrier mobility and leakage currents. Synthesize BiFeO3 with controlled crystalline sizes (bulk vs. nanoscale). Compare magnetic properties (cycloid suppression, weak ferromagnetism emergence) across size regimes. Evaluate transport behavior (resistivity, leakage, and conduction mechanisms) as a function of size and defect concentration. Characterize electronic structure (band gap, optical absorption) and correlate with crystal size and strain. (AU)