장소: 제1과학관 31214  첨단e+강의실 

초록: Since the early 1960’s, we have understood why magnetism is detrimental to conventional superconductivity, but this understanding took an unexpected turn with the 1979 discovery of superconductivity in a very unlikely candidate CeCu2Si2. The surprise was twofold: the Ce ions in CeCu2Si2 were strongly paramagnetic and the electronic specific heat just above the superconducting transition was enormous. With subsequent discoveries of other superconductors like CeCu2Si2, a qualitative understanding began to emerge – magnetism was not detrimental but rather necessary for the unconventional superconductivity in these electronically correlated metals. Experimental observations coupled with theoretical models suggest that quantum fluctuations of magnetic order provide an attractive interaction that creates unconventional superconducting pairs of charge carriers with an effective mass approaching that of a proton. We illustrate that understanding by discussing what is being learned from the recent study of two prototypical examples of the physics, CeCoIn5 and CeRhIn5. Even with this qualitative understanding, these unconventional superconductors present new surprises that are a challenge to experimentalists and theorists alike.

Work at Los Alamos was performed under the auspices of the U.S. Department of Energy, Office of Science, Division of Materials Science and Engineering and in collaboration with Tuson Park, Xin Lu, Zachary Fisk, Eric Bauer, Filip Ronning, Roman Movshovich, Michel Kenzelmann, Hilbert vonLöhneysen and Ali Yazdani.