Effects of B and C Doping on Tunneling Magnetoresistance in CoFe/MgO Magnetic Tunnel Junctions

Authors

Andy Paul Chen, National University of Singapore
John D. Burton, University of Nebraska - Lincoln
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow
Yuan Ping Feng, National University of Singapore
Jingsheng Chen, National University of Singapore

ORCID IDs

Tsymbal http://orcid.org/0000-0002-6728-5565

Document Type

Article

Date of this Version

7-20-2018

Citation

Physical Review B (2018) 98: 045129

doi: 10.1103/PhysRevB.98.045129

Comments

Copyright 2018, American Physical Society. Used by permission

Abstract

Using density-functional theory calculations, we investigate the dominant defects formed by boron (B) and carbon (C) impurities in a CoFe/MgO/CoFe magnetic tunnel junction (MTJ) and their influence on conductivity and tunneling magnetoresistance (TMR). We find that, in the O-poor conditions relevant to experiment, B forms the substitutional defect B_Co and C forms the interstitial site C_i at the CoFe/MgO interface. The C-doped MTJ is predicted to have a significantly higher TMR than the B-doped MTJ. This is due to interface state densities associated with the majority spin Δ₁-symmetry bands being more heavily suppressed by the B_Co defects than by the C_i defects. Our results indicate that carbon can serve as a viable alternative to boron as a dopant for MTJ fabrication.