Spontaneous Symmetry Breaking in the superconducting state of UPt3
Apr. 11, 2012
Joint Research group of Tokyo Institute of Technology, JAEA, Tohoku University, Osaka University and Okayama university have revealed spontaneous symmetry breaking in the superconducting state of a heavy-fermion superconductor UPt3.
Unconventional superconductivity (SC) in the uranium compound UPt3 has attracted attention because of its peculiar superconducting property. Unlike other superconductors, UPt3 has distinct three superconducting phases called A, B and C phase, which appear at different temperature or magnetic field region.
The research group conducted the precise measurement of thermal conductivity as a function of magnetic field direction at very low temperature. The thermal conductivity is, in general, dominated by conduction electron at low temperature. In the present study, a spontaneous symmetry breaking to a two-fold symmetry, which violates the six-fold symmetry arising from the crystal structure, has been detected in the superconducting state (Fig. 1). This result successfully identifies the superconducting symmetry and explains several unsolved properties of UPt3. It is also useful for understanding general aspects of unconventional superconductivity.
This work is published in the journal of American physical society Physical Review LettersE(April 9, 2012): Twofold Spontaneous Symmetry Breaking in the Heavy-Fermion Superconductor UPt3E Y. Machida, A. Itoh, Y. So, K. Izawa, Y. Haga, E. Yamamoto, N. Kimura, Y. Onuki, Y. Tsutsumi, K. Machida, Physical Review Letters 108 157002 (2012).
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