Large energy product enhancement in perpendicularly coupled MnBi/CoFe magnetic bilayers

Authors

T. R. Gao, University of Maryland at College Park
L. Fang, University of Maryland at College Park
S. Fackler, University of Maryland at College Park
S. Maruyama, University of Maryland at College Park
X. H. Zhang, University of Maryland at College Park
L. L. Wang, U.S. Department of Energy
T. Rana, Univeristy of Nebraka - Lincoln
P. Manchanda, University of Nebraska-Lincoln
A. Kashyap, LNM Institute of Information Technology
K. Janicka, U.S. Department of Energy
A. L. Wysocki, U.S. Department of Energy
A. T. N’Diaye, Lawrence Berkeley National Laboratory
E. Arenholz, Lawrence Berkeley National Laboratory
J. A. Borchers, National Institute of Standards and Technology
B. J. Kirby, National Institute of Standards and Technology
B. B. Maranville, National Institute of Standards and Technology
K. W. Sun, U.S. Department of Energy
M. J. Kramer, U.S. Department of Energy
Vladimir P. Antropov, Iowa State UniversityFollow
D. D. Johnson, U.S. Department of Energy
Ralph Skomski, University of Nebraska-LincolnFollow
J. Cui, Pacific Northwest National Laboratory
I. Takeuchi, University of Maryland at College Park

Date of this Version

2016

Citation

PHYSICAL REVIEW B 94, 060411(R) (2016)

Comments

©2016 American Physical Society

Abstract

We demonstrate substantial enhancement in the energy product of MnBi-based magnets by forming robust ferromagnetic exchange coupling between a MnBi layer and a thin CoFe layer in a unique perpendicular coupling configuration, which provides increased resistance to magnetization reversal. The measured nominal energy product of 172 kJ/m³ at room temperature is the largest value experimentally attained for permanent magnets free of expensive raw materials. Our finding shows that exchange-coupled MnBi/CoFe magnets are a viable option for pursuing rare-earth-free magnets with energy products approaching those containing rare-earth elements.