1. Continuous Change of Landau Renormalization from Heavy Fermion to Mixed Valence in Ce1-xYbxCoIn5 Zhaofeng Ding, J. Zhang, C. Tan, K. Huang, Lei Shu (Fudan Univ., Shanghai, China), D. E. MacLaughlin(UC Riverside, CA USA), O. O. Bernal (California State Univ. Los Angeles, CA USA), P.-C. Ho (California State Univ. Fresno, CA USA), I. Lum, M. B. Maple (UC San Diego, CA USA)
Motivation
Linear doping dependence of Tc (red solid dots data :H.Kim et al. 2014, blue squares: Capan et al and black triangles: Shu et al. 2011)
CeCoIn5 has one of the highest transition temperatures among heavy-fermion superconductors, with Tc=2.3K. Striking and unexpected phenomena were observed in Yb substitution of CeCoIn5, such as:
a) Tc decreases linearly towards 0 K with x →1. L. Shu et al. PRL 2011 and C. H. Booth et al. PRB 2011
b) Fermi surface topology change and significant quasiparticle effective mass reduction at x= A. Polyakov et al. PRB 2012
c) Yb valence starts to change around x=0.2. L. Dudy et al. PRB 2013
To understand the change of Fermi-liquid renormalizations from Kondo Heavy Fermion compound(CeCoIn5) to mixed valence compound (YbCoIn5), we performed a systematic study of Muon Spin Relaxation(μSR) experiments on Ce1-xYbxCoIn5, since μSR one of the technique that can measure the absolute value of London penetration depth.
Yb valence of Ce1-xYbxCoIn5 L. Dudy et. al. 2013
Specific heat devided by temperature of Ce1-xYbxCoIn5
L. Shu et. al. 2011
Schematic of a transverse field (TF) μSR setup
MuSR data
Landau Parameters of Ce1-xYbxCoIn5
Asymmetry spectra of Ce1-xYbxCoIn5
The first part stands for the signal from the sample and the second part is the background signal from the silver sample holder and fixed with normal state value
Larger relaxation rate in the superconducting state indicates the inhomogeneous field distribution generated by the formation of flux-line lattice
T dependence of the muon relaxation rate
E. H. Brandt 1988
A. J. Leggett, 1965
Results
F. and H. London 1935
Normalized zero temperature superfluid density was calculated by using the function shown above. As is shown in the right graph, superfluid density decreases continuously with x is increasing.
Table of fitting results
Conclusions
Acknowledgements
Supported by the NSF of China ( and ).