Ab initio evidence for the formation of impurity d_(3z^2-r^2) holes in doped La_(2-x)Sr_xCuO_4
Abstract
Using the spin unrestricted Becke-3-Lee-Yang-Parr density functional, we computed the electronic structure of explicitly doped La2-xSrxCuO4 (x=0.125, 0.25, and 0.5). At each doping level, an impurity hole band is formed within the undoped insulating gap. This band is well localized to CuO6 octahedra adjacent to the Sr impurities. The nature of the impurity hole is A1g in symmetry, formed primarily from the z2 orbital on the Cu and pz orbitals on the apical O's. There is a strong triplet coupling of this hole with the intrinsic B1g Cu x2-y2/O1 pσ hole on the same site. Optimization of the c coordinate of the apical O's in the doped CuO6 octahedron leads to an asymmetric anti-Jahn-Teller distortion of the O_2 atoms toward the central Cu. In particular, the O_2 atom between the Cu and Sr is displaced 0.26 Å while the O_2 atom between the Cu and La is displaced 0.10 Å. Contrary to expectations, investigation of a 0.1 Å enhanced Jahn-Teller distortion of this octahedron does not force formation of an x^2 - y^2 hole, but instead leads to migration of the z^2 hole to the four other CuO_6 octahedra surrounding the Sr impurity. This latter observation offers a simple explanation for the bifurcation of the Sr-O_2 distance revealed in x-ray absorption fine structure data.
Additional Information
© 2002 The American Physical Society. Received 14 November 2001; published 8 March 2002. We wish to acknowledge helpful discussions with Dr. Daniel Haskel and Dr. Peter Schultz. This work was partially supported by the Materials and Process Simulation Center (MSC) at Caltech which is supported by grants from DOE-ASCI, ARO/DURIP, ARO/MURI, 3M, Beckman Institute, Seiko-Epson, Dow, Avery-Dennison, Kellogg, and Asahi Chemical.Attached Files
Published - PERprb02.pdf
Submitted - 0111231.pdf
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Additional details
- Alternative title
- Ab initio evidence for the formation of impurity d3z2-r2 holes in doped La2-xSrxCuO4
- Eprint ID
- 8451
- Resolver ID
- CaltechAUTHORS:PERprb02
- Department of Energy (DOE)
- Army Research Office (ARO)
- 3M
- Caltech Beckman Institute
- Seiko-Epso
- Dow Chemical Company
- Avery-Dennison
- Kellogg
- Asahi Chemical
- Created
-
2007-08-14Created from EPrint's datestamp field
- Updated
-
2021-11-08Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 0504