Synthesis and Properties of Single Domain BiFeO₃ Thin Films and Free-Standing Membranes

BiFeO₃ (BFO) is positioned for success as a magnetoelectric material system, but its optimum usage in faster and more energy-efficient magneto-logic devices require advances. Most importantly, a ferroelastic and antiferromagnetic monodomain state with single-step deterministic switching is desirable for reliable low-power magnetoelectric devices with reproducibility and scaling using BiFeO₃. This would allow deterministic and robust control of both the internal magnetoelectric coupling in BiFeO₃ and the exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer.<br/> <br/>We have fabricated epitaxial (001) and (111) BFO thin films with both ferroelectric and antiferromagnetic monodomain states. Additionally, we have fabricated freestanding membranes of ferroelastic and ferroelectric monodomain BiFeO₃ using an Sr₂CaAl₂O₆ (SCAO) sacrificial layer. The membranes exhibit deterministic switching over a hundred thousand electric field cycles with lower voltage and faster switching dynamics than their thin-film counterpart. This progress is promising toward energy-efficient magnetoelectric memory devices. We will discuss additional multiferroic applications of these BFO membranes.<br/> <br/>This work has been done in collaboration with J. L. Schad, K. J. Lee, Y. Yao, A. M. Vibhakar, R. D. Johnson, P. G. Radaelli M.S. Rzchowski and C.B. Eom.<br/> <br/>CBE acknowledges support for this research through the Gordon and Betty Moore Foundation’s EPiQS Initiative, Grant GBMF9065 and a Vannevar Bush Faculty Fellowship (ONR N00014-20-1-2844). Magnetic and transport measurement at the University of Wisconsin–Madison was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), under award number DE-FG02-06ER46327.