Europhys. Lett, 47 (6), pp. 715-721 (1999)
In-plane charge dynamics in : Absence of a charge gap in the spin/charge ordered state
S. Tajima 1 N. L. Wang 1, N. Ichikawa 2, H. Eisaki 2, S.
Uchida 2, H. Kitano 3
T. Hanaguri 3 and A. Maeda 3
1 Superconductivity Research Laboratory, ISTEC - Tokyo 135-0062, Japan
2 Department of Applied Physics, The University of Tokyo - Tokyo 113-8656, Japan
3 Department of Basic Science, The University of Tokyo - Tokyo 153-0041, Japan
(received 10 June 1999; accepted 13 July 1999)
PACS. 74.25Gz - Optical properties.
PACS. 74.72Dn - La-based cuprates.
PACS. 71.27 - Strongly correlated electron systems; heavy fermions.
We have investigated the optical conductivity of the spin/charge "stripe'' order phase in in the microwave and the infrared regions. The in-plane conductivity is appreciably suppressed with respect to the spectrum for the Nd-free crystal over a wide frequency range of up to . The suppression persists even at room temperature, indicating a strong fluctuation of this order. Nevertheless, the spectrum is basically metallic without showing a gap associated with charge order. It was found that the magnetic penetration depth is extremely long in the superconducting state which coexists with the static spin/charge order.
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