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Title: Are the Surfaces of CrO2 Metallic?

Abstract

Previous photoelectron spectroscopy studies of CrO2 have found either no density of states or a very low density of states at the Fermi level, suggesting that CrO2 is a semiconductor or a semi-metal. This is in contradiction to calculations that predict that CrO2 should be a half-metallic ferromagnet. Recently, techniques have been developed to grow high-quality epitaxial films of CrO2 on TiO2 substrates by chemical vapour deposition. We present photoelectron spectroscopy measurements of epitaxial CrO2(110)/TiO2(110) and CrO2(100)/TiO2(100) grown using a CrO3 precursor. In addition, measurements of epitaxial Cr2O3(0001)/Pt(111) films grown by thermal evaporation of Cr in an oxygen atmosphere are presented as a reference for reduced CrO2 films. The measurements of the CrO2 surfaces show no emission at the Fermi level after sputtering and annealing the surfaces in oxygen, even though our soft core photoemission data and low-energy electron diffraction measurements provide evidence that stoichiometric CrO2 is present. The consequence of this is that neither surface of CrO2 is metallic. This behaviour could result from a metal to semiconductor transition at the (110) and (100) surfaces.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959713
Report Number(s):
BNL-82699-2009-JA
Journal ID: ISSN 0953-8984; JCOMEL; TRN: US201016%%857
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics: Condensed Matter; Journal Volume: 19
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; DEPOSITION; ELECTRON DIFFRACTION; EVAPORATION; FERMI LEVEL; OXYGEN; PHOTOELECTRON SPECTROSCOPY; PHOTOEMISSION; PRECURSOR; SPUTTERING; SUBSTRATES; SURFACES; national synchrotron light source

Citation Formats

Ventrice, Jr.,C., Borst, D., Geisler, H., van Ek, J., Losovyj, Y., Robbert, P., Diebold, U., Rodriguez, J., Miao, G., and Gupta, A. Are the Surfaces of CrO2 Metallic?. United States: N. p., 2007. Web. doi:10.1088/0953-8984/19/31/315207.
Ventrice, Jr.,C., Borst, D., Geisler, H., van Ek, J., Losovyj, Y., Robbert, P., Diebold, U., Rodriguez, J., Miao, G., & Gupta, A. Are the Surfaces of CrO2 Metallic?. United States. doi:10.1088/0953-8984/19/31/315207.
Ventrice, Jr.,C., Borst, D., Geisler, H., van Ek, J., Losovyj, Y., Robbert, P., Diebold, U., Rodriguez, J., Miao, G., and Gupta, A. Mon . "Are the Surfaces of CrO2 Metallic?". United States. doi:10.1088/0953-8984/19/31/315207.
@article{osti_959713,
title = {Are the Surfaces of CrO2 Metallic?},
author = {Ventrice, Jr.,C. and Borst, D. and Geisler, H. and van Ek, J. and Losovyj, Y. and Robbert, P. and Diebold, U. and Rodriguez, J. and Miao, G. and Gupta, A.},
abstractNote = {Previous photoelectron spectroscopy studies of CrO2 have found either no density of states or a very low density of states at the Fermi level, suggesting that CrO2 is a semiconductor or a semi-metal. This is in contradiction to calculations that predict that CrO2 should be a half-metallic ferromagnet. Recently, techniques have been developed to grow high-quality epitaxial films of CrO2 on TiO2 substrates by chemical vapour deposition. We present photoelectron spectroscopy measurements of epitaxial CrO2(110)/TiO2(110) and CrO2(100)/TiO2(100) grown using a CrO3 precursor. In addition, measurements of epitaxial Cr2O3(0001)/Pt(111) films grown by thermal evaporation of Cr in an oxygen atmosphere are presented as a reference for reduced CrO2 films. The measurements of the CrO2 surfaces show no emission at the Fermi level after sputtering and annealing the surfaces in oxygen, even though our soft core photoemission data and low-energy electron diffraction measurements provide evidence that stoichiometric CrO2 is present. The consequence of this is that neither surface of CrO2 is metallic. This behaviour could result from a metal to semiconductor transition at the (110) and (100) surfaces.},
doi = {10.1088/0953-8984/19/31/315207},
journal = {Journal of Physics: Condensed Matter},
number = ,
volume = 19,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}