Hole distribution in ( Sr , Ca , Y , La ) 14 <mml:mi mathvariant="…
2000; American Physical Society; Volume: 62; Issue: 21 Linguagem: Inglês
10.1103/physrevb.62.14384
ISSN1095-3795
AutoresN. Nücker, Michael Merz, C. A. Kuntscher, Stefan Gerhold, S. Schuppler, R. Neudert, M. S. Golden, J. Fink, Dieter Schild, Shane Stadler, V. Chakarian, J. W. Freeland, Y. U. Idzerda, K. Conder, M. Uehara, Takashi Nagata, Junya Goto, Jun Akimitsu, N. Motoyama, Hiroshi Eisaki, Satoshi Uchida, U. Ammerahl, A. Revcolevschi,
Tópico(s)Magnetic and transport properties of perovskites and related materials
ResumoThe unoccupied electronic structure for the ${\mathrm{Sr}}_{14}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}$ family of two-leg ladder compounds was investigated for different partial substitutions of ${\mathrm{Sr}}^{2+}$ by ${\mathrm{Ca}}^{2+},$ leaving the nominal hole count constant, and by ${\mathrm{Y}}^{3+}$ or ${\mathrm{La}}^{3+},$ reducing the nominal hole count from its full value of 6 per formula unit. Using polarization-dependent x-ray absorption spectroscopy on single crystals, hole states on both the chain and ladder sites could be studied. While for intermediate hole counts all holes reside on O sites of the chains, a partial hole occupation on the ladder sites in orbitals oriented along the legs is observed for the fully doped compound ${\mathrm{Sr}}_{14}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}.$ On substitution of Ca for Sr orbitals within the ladder planes but perpendicular to the legs receive some hole occupation as well.
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