Thickness-dependent magnetism and spin-glass behaviors in compressively strained BiFeO3 thin films

Compressively strained BiFeO3 (BFO) films from 19 to 114 nm are epitaxially grown on LaAlO3 substrates, and their thickness-dependent evolutions of structural and magnetic properties are investigated. Across the morphotropic phase boundary, complex strain relaxation behaviors involving low-symmetry intermediate/bridging phases are observed. The fully strained 38 nm BFO film exhibits a saturation magnetization of similar to 28 emu/cm(3) at 300 K with a coercivity of 130 Oe while all films show a spin-glass behavior. These findings suggest that tailoring film thickness is effective to suppress the cycloidal magnetic modulation in BFO, leading to magnetic properties different from the bulk counterpart. (C) 2011 American Institute of Physics. [doi:10.1063/1.3600064]