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 Selvan Sakthivel; Chenze Liu; Mark Hettick; Rupam Mukherjee; Sudipta Seal; Lane W Martin; Ali Javey; Gerd Duscher; Ramamoorthy Ramesh; Ramki Kalyanaraman

doi:10.1038/s41598-020-58592-5

Integration of amorphous ferromagnetic oxides with multiferroic materials for room temperature magnetoelectric spintronics

Sci Rep. 2020 Feb 27;10(1):3583. doi: 10.1038/s41598-020-58592-5.

Authors

Humaira Taz^#^{1

2}, Bhagwati Prasad^#³, Yen-Lin Huang¹, Zuhuang Chen^{1

4}, Shang-Lin Hsu¹, Ruijuan Xu¹, Vishal Thakare¹, Tamil Selvan Sakthivel⁵, Chenze Liu⁶, Mark Hettick⁷, Rupam Mukherjee⁸, Sudipta Seal⁹, Lane W Martin^{1

10}, Ali Javey⁷, Gerd Duscher⁶, Ramamoorthy Ramesh¹¹, Ramki Kalyanaraman^{12

13}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
² Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.
³ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA. bprasadiitk@gmail.com.
⁴ School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055, P. R. China.
⁵ Advanced Materials Processing and Analysis Center (AMPAC, Materials Science and Engineering (MSE) Department, University of Central Florida, Orlando, FL, 32816, USA.
⁶ Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA.
⁷ Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, 94720, USA.
⁸ Department of Physics, Lovely Professional University, Phagwara, Punjab, 144411, India.
⁹ College of Medicine, University of Central Florida, Orlando, FL, 32827, USA.
¹⁰ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA.
¹¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA. rramesh@berkeley.edu.
¹² Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA. ramki@utk.edu.
¹³ Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, 37996, USA. ramki@utk.edu.

^# Contributed equally.

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_0.66Dy_0.24Tb_0.1)₃O_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 BiFeO₃. A strong enhancement in the magnetic coercive field of FDTO grown on BiFeO₃ validated a large exchange coupling between them. Additionally, FDTO served as an excellent top electrode for ferroelectric switching in BiFeO₃ with no sign of degradation after ~10¹⁰ switching cycles. RT magneto-electric coupling was demonstrated by modulating the resistance states of spin-valve structures using electric fields.