Electronic States of Doped Spin Ladders (Sr,Ca)_<14>Cu_<24>O_<41>

概要

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We examine the electronic states of Sr),j .Ca.Cu3,jO,jj by the tonic and cluster naodel ap-proach. It is found that self-doped holes are likely to stay on the chain at x : 0 and Casubstitution drives the holes to move to the ladder. This feature is caused by changes of the po-sitions of (Sr,Ca) layers, which results in enhancement of the electrostatic potentials in the chain.The optical conductivity is calculated with application of the exact diagonalization method tosrnall Cu-O clusters. It is shown that the excitations below 2 eV are governed by the ladder,giving rise to the spectral weight transfer frotaa the charge-transfer excitation at around 2 eV tolow energy Drude excitation, while the contribtrtion from the chain mainly enuerges in a higherenergy reguon showing large spectral weight at around 3 eV. These findings provide a consistentexplanation for the results of a recent experirnent.
社団法人日本物理学会の論文
1997-04-15