Issue
EPL
Volume 87, Number 4, August 2009
Article Number 47006
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/87/47006
Published online 07 September 2009
EPL, 87 (2009) 47006
DOI: 10.1209/0295-5075/87/47006

Anomalous bias dependence in magnetic tunnel junctions based on half-metallic $\chem{CrO_{2}}$ with heteroepitaxial $\chem{SnO_{2}}$ tunnel barrier

Guo-Xing Miao1, 2, Gang Xiao2 and Arunava Gupta1

1   MINT center, University of Alabama - Tuscaloosa, AL 35487, USA
2   Physics Department, Brown University - Providence, RI 02912, USA

gxmiao@mit.edu

received 29 June 2009; accepted in final form 5 August 2009; published August 2009
published online 7 September 2009

Abstract
We report on the anomalous bias dependence of tunneling magnetoresistance (TMR) in ( ${\rm CrO}_{2}/{\rm SnO}_{2}/{\rm Co}$)-based magnetic tunnel junctions as a function of barrier thickness. For a relatively thin ${\rm SnO}_{2}$ barrier, the TMR is asymmetric and exhibits sign reversal at a specific bias voltage with varying thickness due to defect mediated resonant tunneling. On the other hand, diffusive transport dominates for sufficiently thick ${\rm SnO}_{2}$ barriers, and a diverging TMR is observed close to zero bias.

PACS
73.40.Gk - Tunneling.
72.25.-b - Spin polarized transport.
73.40.Sx - Metal-semiconductor-metal structures.

© EPLA 2009