Europhys. Lett.
Volume 72, Number 3, November 2005
Page(s) 458 - 464
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 30 September 2005
Europhys. Lett., 72 (3), pp. 458-464 (2005)
DOI: 10.1209/epl/i2005-10247-3

High-pressure effects in fluorinated $\chem{HgBa_2Ca_2Cu_3O_{8+\delta}}$

M. Monteverde1, 2, C. Acha2, M. Núñez-Regueiro1, D. A. Pavlov3, K. A. Lokshin3, S. N. Putilin3 and E. V. Antipov3

1  CRTBT, CNRS - BP166, 38042 Grenoble Cedex 09, France
2  Laboratorio de Bajas Temperaturas, Departamento de Física, FCEyN Universidad de Buenos Aires, Ciudad Universitaria (C1428EHA) Buenos Aires, Argentina
3  Department of Chemistry, Moscow State University - Moscow 119992, Russia

received 25 April 2005; accepted 7 September 2005
published online 30 September 2005

We have measured the pressure sensitivity of Tc in fluorinated $\chem{HgBa_2Ca_2Cu_3O_{8+\delta}}$ (Hg-1223) ceramic samples with different F contents, applying pressures up to 30$\un{GPa}$. We obtained that Tc increases with increasing pressure, reaching different maximum values, depending on the F doping level, and decreases for a further increase of pressure. A new high Tc record ( $166 \un{K} \pm 1 \un{K}$) was achieved by applying pressure (23$\un{GPa}$) in a fluorinated Hg-1223 sample near the optimum doping level. Our results show that all our samples are at the optimal doping, and that fluorine incorporation decreases the crystallographic a-parameter concomitantly increasing the maximum attainable Tc. This effect reveals that the compression of the a-axis is one of the keys that controls the Tc of high-temperature superconductors.

74.72.Jt - Other cuprates, including Tl and Hg-based cuprates.
74.62.Fj - Pressure effects.

© EDP Sciences 2005