Quantum tricritical fluctuations driving mass enhancement and reentrant superconductivity in URhGe

TMU International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure"

Tokunaga, Y.^1 ; Aoki, D.^2,3 ; Mayaffre, H.^4 ; Krämer, S.^4 ; Julien, M.-H.^4 ; Berthier, C.^4 ; Horvati, M.^4 ; Sakai, H.^1 ; Kambe, S.^1 ; Hattori, T.^1 ; Araki, S.^2,5

ASRC, Japan Atomic Energy Agency Tokai, Ibaraki

319-1195, Japan^1

INAC/SPSMS, CEA-Grenoble/UJF, Grenoble

38054, France^2

IMR, Tohoku University, Ibaraki

311-1313, Japan^3

LNCMI, UPR 3228, CNRS-UJF-UPS-INSA, Grenoble

38042, France^4

Department of Physics, Okayama University, Okayama

700-8530, Japan^5

关键词: Conduction electrons;    Ferromagnetic superconductor URhGe;    Quantum critical fluctuations;    Quantum critical points;    Re-entrant superconductivity;    Spin-spin relaxation;    Superconductivity and magnetism;    Tricritical point;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/683/1/012010/pdf
DOI  :  10.1088/1742-6596/683/1/012010

来源: IOP

【 摘 要 】

The field-induced reentrant superconductivity (RSC) discovered near a quantum critical point (QCP) in a ferromagnetic superconductor URhGe highlights the close interplay between superconductivity and magnetism. While the origin of the RSC is broadly thought to be associated with quantum critical fluctuations, their exact nature had not been well identified. Here we review our recent59Co NMR study in a single crystal of URh0.9Co0.1Ge. Our measurements of the NMR spin-spin relaxation reveal a divergence of electronic spin fluctuations in the vicinity of the field-induced QCP at HR≈ 13 T. The fluctuations observed are characteristic of a tricritical point, followed by a phase bifurcation toward quantum wing-critical points. We show that these tricritical fluctuations enhance the effective mass of the conduction electrons and, further, drive the RSC near the HR.