Quantum phase transition inside superconducting dome

Hong Xiao

Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China


    It is an open question regarding the universality of the existence of a quantum critical point (QCP) inside the superconducting (SC) dome of unconventional superconductor and if such a QCP is responsible for the unconventional superconductivity and the non-Fermi liquid (NFL) behavior. In this talk, I will show several examples to discuss this problem. For example, antiferromagnetic (AF) QCP is present inside the SC dome of CeCoIn5 and is believed to be responsible for the NFL behavior in the normal state. In addition, AF, SC and QCP are intimately correlated. However, in Yb doped CeCoIn5, it is observed that the full suppression of QCP has surprisingly little impact on both unconventional superconductivity and non-Fermi liquid behavior. Furthermore, in iron-based superconductor, Co doped BaFe2AS2, a first order AF quantum phase transition (QPT) is found inside the SC dome and the SC in this system is closely related with this QPT. A magnetic tricritical point might exist in T-P plane and no QCP is expected in zero magnetic field.

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