Zero-bias anomaly in $\chem{CrO_2}$ junctions

A. Sokolov; C.-S. Yang; L. Yuan; S.-H. Liou; Ruihua Cheng; H.-K. Jeong; T. Komesu; B. Xu; C. N. Borca; P. A. Dowben; B. Doudin

doi:doi:10.1209/epl/i2002-00659-y

DOI: 10.1209/epl/i2002-00659-y

Europhys. Lett., 58 (3) , pp. 448-454 (2002)

Zero-bias anomaly in $\chem{CrO_2}$ junctions

A. Sokolov, C.-S. Yang, L. Yuan, S.-H. Liou, Ruihua Cheng, H.-K. Jeong, T. Komesu, B. Xu, C. N. Borca, P. A. Dowben and B. Doudin

Center for Materials Research and Analysis and Department of Physics and Astronomy Behlen Laboratory of Physics, University of Nebraska - Lincoln, NE 68588-0111, USA

(Received 12 October 2001; accepted in final form 5 February 2002)

Abstract
$\chem{CrO_2}$ thin films, with crystallites of several microns size, provide the opportunity for the investigation of the intergrain tunneling between a few crystals separated by a 1-2 $\un{nm}$ thick $\chem{Cr_2O_3}$ film. A pronounced zero-bias anomaly of the conductance is found at low temperatures. Combined photoemission and inverse photoemission temperature-dependent studies confirm the occurrence of Coulomb blockade. For the strong-tunneling case ( $R \ll R_{\ab{Q}} = h/2e^2$ ), the magnetoresistance decreases strongly with bias. For the weak-tunneling case ( $R \gg R_{\ab{Q}}$ ), the magnetoresistance decreases by a factor two with increasing bias, as predicted by a co-tunneling model.

PACS
75.70.-i - Magnetic properties of thin films, surfaces, and interfaces.
81.15.Gh - Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, etc.).
82.30.Lp - Decomposition reactions (pyrolysis, dissociation, and fragmentation).

© EDP Sciences 2002

Zero-bias anomaly in junctions

Zero-bias anomaly in $\chem{CrO_2}$ junctions