Near-band gap electronic structure of the tetragonal rare-earth cuprates R2CuO4 and the bismuth cuprate Bi2CuO4 / Pisarev R. V.,Pavlov V. V.,Kalashnikova A. M.,Moskvin A. S. // PHYSICAL REVIEW B. - 2010. - V. 82, l. 22.

ISSN/EISSN:

1098-0121 / нет данных

Type:

Article

Abstract:

Complex optical dielectric function in the tetragonal rare-earth cuprates R2CuO4 (R=La, Pr, Nd, and Sm) and in the tetragonal bismuth cuprate Bi2CuO4 is studied in the spectral range of 0.6-5.4 eV using a method of optical ellipsometry. The dielectric spectra are studied for the two main polarizations and analyzed in terms of a cluster model for CuO46- complexes taking into account intracenter p-d and intercenter d-d charge-transfer (CT) transitions. The band gap in the rare-earth cuprates is defined by an electric-dipole-allowed CT transitions centered at 1.54-1.59 eV in Pr, Nd, and Sm cuprates, and 2.1 eV in La cuprate. Optical response of Bi2CuO4 strongly differs from the rare-earth cuprates which we relate with strong covalency of Bi-O bonding and strong ionicity of Cu(3d)-O(2p) bonding. These features are manifested in suppression of low-energy intense intracenter p-d and intercenter d-d CT transitions, and by appearance of strong intense absorption bands near 5 eV. Regardless the strong distinctions of optical response, on one hand, of La, Pr, Nd, and Sm cuprates, and on the other hand, of the Bi cuprate, the dielectric gap in these compounds shows comparable values defined by a superposition of intracenter p-d CT transitions and two-center d-d CT transitions. Thus these cuprates should be classified as compounds intermediate between CT and Mott-Hubbard insulators.

Author keywords:

CHARGE-TRANSFER EXCITATION; DEPENDENCE; CRYSTAL; TRANSITIONS; MANGANITES; ANISOTROPY; CUO; SM

DOI:

10.1103/PhysRevB.82.224502

Web of Science ID:

ISI:000286752700005

Соавторы в МНС:

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Другие поля

Поле	Значение
Month	DEC 1
Publisher	AMER PHYSICAL SOC
Address	ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Language	English
Article-Number	224502
Keywords-Plus	CHARGE-TRANSFER EXCITATION; DEPENDENCE; CRYSTAL; TRANSITIONS; MANGANITES; ANISOTROPY; CUO; SM
Research-Areas	Physics
Web-of-Science-Categories	Physics, Condensed Matter
ResearcherID-Numbers	Kalashnikova, Alexandra/C-7821-2014 Pavlov, Victor/E-1976-2014
ORCID-Numbers	Kalashnikova, Alexandra/0000-0001-5635-6186
Funding-Acknowledgement	RFBR {[}08-02-00633, 09-02-00070, 10-02-96032]; Russian Agency for Science and Innovations {[}02.740.11.0384]; Dutch nanotechnology initiative NanoNed
Funding-Text	Samples used in the present study were prepared from bulk single crystals kindly provided by S. N. Barilo, V. P. Plakhty, V. V. Popov, K. A. Sablina, and V. A. Sanina. A. S. Moskvin thanks S.-L. Drechsler and R. Hayn for useful discussions. Part of this work was performed under the Joint RFBR-NWO Project (2006-2008) and we thank the Dutch coordinator of the Project Th. Rasing for providing facilities for ellipsometry measurements. This research was supported in part by RFBR under Projects No. 08-02-00633, No. 09-02-00070, and No. 10-02-96032, by the Russian Agency for Science and Innovations under the Contract No. 02.740.11.0384, and Dutch nanotechnology initiative NanoNed.
Number-of-Cited-References	41
Usage-Count-Last-180-days	7
Usage-Count-Since-2013	50
Journal-ISO	Phys. Rev. B
Doc-Delivery-Number	713QO