Integration of amorphous ferromagnetic oxides with multiferroic materials for room temperature magnetoelectric spintronics
Humaira Taz, Bhagwati Prasad, Yen-Lin Huang, Zuhuang Chen, Shang-Lin Hsu, Ruijuan Xu, Vishal Thakare, Tamil S. Sakthivel, Chenze Liu, Mark Hettick, Rupam Mukherjee, Sudipta Seal, Lane W. Martin, Ali Javey, Gerd Duscher, R. Ramesh, R. Kalyanaraman
Abstract
Abstract A room temperature amorphous ferromagnetic oxide semiconductor can substantially reduce the cost and complexity associated with utilizing crystalline materials for spintronic devices. We report a new material (Fe 0.66 Dy 0.24 Tb 0.1 ) 3 O 7-x (FDTO), which shows semiconducting behavior with reasonable electrical conductivity (~500 mOhm-cm), an optical band-gap (2.4 eV), and a large enough magnetic moment (~200 emu/cc), all of which can be tuned by varying the oxygen content during deposition. Magnetoelectric devices were made by integrating ultrathin FDTO with multiferroic BiFeO 3 . A strong enhancement in the magnetic coercive field of FDTO grown on BiFeO 3 validated a large exchange coupling between them. Additionally, FDTO served as an excellent top electrode for ferroelectric switching in BiFeO 3 with no sign of degradation after ~10 10 switching cycles. RT magneto-electric coupling was demonstrated by modulating the resistance states of spin-valve structures using electric fields.