Fully gapped d-wave superconductivity in CeCu2Si2

Guiming Pang; Michael Smidman; Jinglei Zhang; Lin Jiao; Zongfa Weng; Emilian M Nica; Ye Chen; Wenbing Jiang; Yongjun Zhang; Wu Xie; Hirale S Jeevan; Hanoh Lee; Philipp Gegenwart; Frank Steglich; Qimiao Si; Huiqiu Yuan

doi:10.1073/pnas.1720291115

Fully gapped d-wave superconductivity in CeCu₂Si₂

Proc Natl Acad Sci U S A. 2018 May 22;115(21):5343-5347. doi: 10.1073/pnas.1720291115. Epub 2018 May 8.

Authors

Guiming Pang^{1

2}, Michael Smidman^{1

2}, Jinglei Zhang^{1

2}, Lin Jiao^{3

2}, Zongfa Weng^{1

2}, Emilian M Nica^{4

5

6}, Ye Chen^{1

2}, Wenbing Jiang^{1

2}, Yongjun Zhang^{1

2}, Wu Xie^{1

2}, Hirale S Jeevan^{1

2

7}, Hanoh Lee^{1

2}, Philipp Gegenwart⁷, Frank Steglich^{1

2

8}, Qimiao Si⁴, Huiqiu Yuan^{3

2

9}

Affiliations

¹ Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China.
² Department of Physics, Zhejiang University, Hangzhou 310027, China.
³ Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China; hqyuan@zju.edu.cn phyman21@gmail.com.
⁴ Department of Physics and Astronomy, Rice University, Houston, TX 77005.
⁵ Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
⁶ Quantum Materials Institute, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
⁷ Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany.
⁸ Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.
⁹ Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.

Abstract

The nature of the pairing symmetry of the first heavy fermion superconductor CeCu₂Si₂ has recently become the subject of controversy. While CeCu₂Si₂ was generally believed to be a d-wave superconductor, recent low-temperature specific heat measurements showed evidence for fully gapped superconductivity, contrary to the nodal behavior inferred from earlier results. Here, we report London penetration depth measurements, which also reveal fully gapped behavior at very low temperatures. To explain these seemingly conflicting results, we propose a fully gapped [Formula: see text] band-mixing pairing state for CeCu₂Si₂, which yields very good fits to both the superfluid density and specific heat, as well as accounting for a sign change of the superconducting order parameter, as previously concluded from inelastic neutron scattering results.

Keywords: CeCu2Si2; heavy fermions; multiband superconducting pairing; penetration depth; superconducting order parameter.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.