Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors

^†Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;
^§IBM T. J. Watson Research Center, Yorktown Heights, NY 10598;
^¶Department of Materials Science and Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan; and
^‖Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan

Edited by Sudip Chakravarty, University of California, Los Angeles, CA, and accepted by the Editorial Board March 4, 2008 (received for review December 28, 2007)

Abstract

In high-transition-temperature (T _c) superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet to the superconducting region. In the metallic state above T _c, the standard Landau's Fermi-liquid theory of metals as typified by the temperature squared (T ²) dependence of resistivity appears to break down. Whether the origin of the non-Fermi-liquid behavior is related to physics specific to the cuprates is a fundamental question still under debate. We uncover a transformation from the non-Fermi-liquid state to a standard Fermi-liquid state driven not by doping but by magnetic field in the overdoped high-T _c superconductor Tl₂Ba₂CuO_6+x. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid features appear above a sufficiently high field that decreases linearly with temperature and lands at a quantum critical point near the superconductivity's upper critical field—with the Fermi-liquid coefficient of the T ² dependence showing a power-law diverging behavior on the approach to the critical point. This field-induced quantum criticality bears a striking resemblance to that in quasi-two-dimensional heavy-Fermion superconductors, suggesting a common underlying spin-related physics in these superconductors with strong electron correlations.

Footnotes

^‡To whom correspondence should be addressed. E-mail: shibauchi{at}scphys.kyoto-u.ac.jp
Author contributions: T.S. and L.K.-E. designed research; T.S., L.K.-E., M.H., Y.K., and R.O. performed research; T.S. and L.K.-E. analyzed data; and T.S., L.K.-E., and Y.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. S.C. is a guest editor invited by the Editorial Board.