Europhys. Lett.
Volume 67, Number 6, September 2004
Page(s) 1018 - 1023
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 September 2004
Europhys. Lett., 67 (6), pp. 1018-1023 (2004)
DOI: 10.1209/epl/i2004-10199-0

Observation of the pseudogap in the heavily overdoped high-temperature superconductor $\chem{La_{1.71}Sr_{0.25}Ho_{0.04}CuO_{4}}$

P. S. Häfliger, A. Podlesnyak, K. Conder, E. Pomjakushina and A. Furrer

Laboratory for Neutron Scattering, ETH Zurich & PSI Villigen CH-5232 Villigen PSI, Switzerland

(Received 7 May 2004; accepted in final form 27 July 2004)

We studied the relaxation behavior of crystal-field transitions in the heavily overdoped high-temperature superconductor $\chem{La_{1.71}Sr_{0.25}Ho_{0.04}CuO_{4}}$ ( $T_{\ab{C}}\approx
10$ $\un{K}$) by neutron spectroscopic experiments. There is clear evidence for the opening of the pseudogap at $T^*=(46.5\pm 0.5)$ $\un{K}$ and $T^*=(48.4\pm 1.4)$ $\un{K}$ for the $\chem{{}^{16}O}$ and $\chem{{}^{18}O}$ compound, respectively. The fact that the pseudogap phenomenon extends far into the overdoped region supports the theoretical view of the existence of preformed pairs at $T^*>T_{\ab{C}}$.

74.72.Dn - $\chem{La}$-based cuprates.
76.30.Kg - Rare-earth ions and impurities.
78.70.Nx - Neutron inelastic scattering.

© EDP Sciences 2004