11th Materials Science School for Young Scientists and Students 2014 (KINKEN-WAKATE 2014)

Fundamentals and Modern Aspects of Superconductivity

Prof. Yasutomo J. Uemura

HEADLINE

Muon Spin Relaxation Studies of Unconventional Superconductors　

　Since the discovery of the cuprate systems, we have performed muon spin relaxation experiments on various unconventional superconductors and demonstrated that the superconducting Tc nearly scales with the zero-temperature superfluid density in underdoped cuprates, overdoped Tl2201, Zn doped LSCO/YBCO, and Alkali doped C60. The nearly linear relationship of these systems are also followed by various other superconductors including organic 2-d BEDT, some heavy fermions, and several FeAs-based systems.

　We disciss possible relevance of this behavior to the concepts of Bose-Einstein to BCS crossover in condensation, roton-like spin excitations, and resonance of spin and charge energy scales which might provide a key to understand the pairing mechanisms.