講演題目: Cuprate superconductivity: still searching for the right mechanism.
講師: William Sacks 氏(Sorbonne University/Okayama Univ. )
日時: 2025年11月21日(金) 15:30-16:30
場所: 北海道大学理学部2号館2-211 室
要旨:
Despite thousands of experiments on cuprate superconductors over
more than three decades, and numerous theoretical proposals, the
mechanism of high-Tc superconductivity remains unresolved.
Researchers have extensively investigated the resistivity, magnetic
susceptibility, specific heat, and quasiparticle spectra (ARPES and
tunneling) of the cuprate family. However, their interpretation often
remains ambiguous or even contradictory, hindering a unified
understanding of the key physical parameters. Fundamental
concepts—such as spin fluctuations, quantum criticality, and preformed
pairs—continue to be debated, but so far a satisfactory match to
experiment is still lacking.
In this seminar, we describe the pairon model [1] of cuprate
superconductivity in which preformed hole pairs are bound by their
local antiferromagnetic (AF) environment. The pairon condensation
mechanism provides a clear and coherent picture of the unconventional
superconducting state, compatible with a wide range of experiments
[1-5].
Remarkably, the model allows the derivation of an explicit formula for
the critical temperature, TC. As a result, the proposed phase diagram
can be understood in terms of a single energy scale, the
antiferromagnetic exchange energy, J .