Suppression of the charge-density-wave state in Sr14Cu24O41 by calcium doping.
The charge response in the spin chain and/or ladder compound Sr14-xCaxCu24O41 is characterized by dc resistivity, low-frequency dielectric spectroscopy and optical spectroscopy. We identify a phase transition below which a charge-density wave (CDW) develops in the ladder arrays. Calcium doping suppresses this phase with the transition temperature decreasing from 210 K for x=0 to 10 K for x=9, and the CDW gap from 130 meV down to 3 meV, respectively. This suppression is due to the worsened nesting originating from the increase of the interladder tight-binding hopping integrals, as well as from disorder introduced at the Sr sites. These results altogether speak in favor of two-dimensional superconductivity under pressure.
Vuletić
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Institut za fiziku, P.O. Box 304, HR-10001 Zagreb, Croatia. tvuletic@ifs.hr
Korin-Hamzić
B
B
Tomić
S
S
Gorshunov
B
B
Haas
P
P
Rõõm
T
T
Dressel
M
M
Akimitsu
J
J
Sasaki
T
T
Nagata
T
T