[JRG Seminar] Superconductivity induced by spin fluctuation around magnetic phase
* SPEAKERS
Name
Affiliation
E-mail
Dr. Tetsuya Takimoto
APCTP
Prof. Ki-Seok kim(APCTP) kimks(at)apctp.org
* HOST(Applicant)
Name
Affiliation
E-mail
-
* DATE / TIME
2009-04-22, 1pm
* PLACE
Seminar Room 512, APCTP Headquarters, Pohang, Korea
* ABSTRACT
In the three dimensional electron (Fermi liquid) system, the second-order coefficient of free energy with respect to the magnetic order parameter, namely the inverse susceptibility of the order parameter, vanishes at the magnetic phase transition of second-order. This means that the spin fluctuation develops around the magnetic transition. Then, the critical spin fluctuation contributes to various quantities like the specific heat. Especially, when the transition temperature becomes 0K, called as the quantum critical point (QCP), the critical spin fluctuation gives an contribution of non-Fermi-liquid behavior. Unconventional superconductivity is also observed around QCP, where the superconductivity will be induced by the critical spin fluctuation. In the two dimensional case, the magnetic transition does not occur at finite temperature due to the Mermin-Wagner theorem. The disorder property will bring some differences in spectra of spin fluctuation. Actually, the superconducting phase around the magnetic phase is affected by changing the dimensionality of system. Comparing the phase diagrams of CeIn3 (3D) and CeTIn5 (quasi-2D), we will discuss these things, based on the self-consistent renormalization (SCR) theory and the fluctuation exchange (FLEX) approximation. If we will have plenty of time after the discussion, we also discuss the effect of orbital fluctuation on superconductivity in the orbital degenerate system.
