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

Date of this Version

7-20-2018

Citation

Physical Review B 98, 045129 (2018).
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.