Anomalous Behavior of the Thermoelectric Power in the Vicinity of the Superconducting Transition in the Organic Superconductors $\mathsf{\kappa}$-(BEDT-TTF)$\mathsf{_2}$Cu(NCS)$\mathsf{_2}$ and $\mathsf{\kappa}$-(BEDT-TTF)$\mathsf{_2}$Cu[ N(CN)$\mathsf{_2}$] Br

G.Yu. Logvenov; M.V. Kartsovnik; H. Ito; T. Ishiguro; M. Kund; G. Saito; S. Takasaki; J. Yamada; H. Anzai

doi:doi:10.1051/jp1:1996203

Numéro		J. Phys. I France Volume 6, Numéro 12, December 1996


Page(s)		2051 - 2060
DOI		https://doi.org/10.1051/jp1:1996203

DOI: 10.1051/jp1:1996203
J. Phys. I France 6 (1996) 2051-2060

Anomalous Behavior of the Thermoelectric Power in the Vicinity of the Superconducting Transition in the Organic Superconductors $\mathsf{\kappa}$ -(BEDT-TTF) $\mathsf{_2}$ Cu(NCS) $\mathsf{_2}$ and $\mathsf{\kappa}$ -(BEDT-TTF) $\mathsf{_2}$ Cu[ N(CN) $\mathsf{_2}$ ] Br

G.Yu. Logvenov^{1, 2}, M.V. Kartsovnik¹, H. Ito², T. Ishiguro², M. Kund³, G. Saito², S. Takasaki⁴, J. Yamada⁴ and H. Anzai⁴

¹ Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, Moscow district, 142432, Russia
² Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-01, Japan
³ Walther-Meissner-Institute für Tieftemperaturforschung, Walther-Meissner-Strasse 8, Garching, 85748, Germany
⁴ Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo 678-12, Japan

(Received 10 March 1996, revised 20 April 1996, accepted 11 June 1996)

Abstract
The in-plane thermoelectric power (TEP) of the layered organic superconductors $\kappa$ -(BEDT-TTF) ₂Cu(NCS) ₂ and $\kappa$ -(BEDT-TTF) ₂Cu[ N(CN) ₂] Br has been studied in the vicinity of the superconducting transition under magnetic field. Below the transition temperature, an anomalous non-monotonic behavior of the TEP is found in the $\kappa$ -(BEDT-TTF) ₂Cu(NCS) ₂ salt: instead of a gradual monotonic decrease, the TEP shows a prominent sign-change before vanishing. Similar, although less pronounced features have been found in the other compound. The change in sign of the TEP is explained in terms of the two-fluid counterflow model, assuming a predominant role of one of the two anisotropic bands (namely, the electron-like one) in the superconducting pairing.

Anomalous Behavior of the Thermoelectric Power in the Vicinity of the Superconducting Transition in the Organic Superconductors -(BEDT-TTF) Cu(NCS) and -(BEDT-TTF) Cu[ N(CN) ] Br

Anomalous Behavior of the Thermoelectric Power in the Vicinity of the Superconducting Transition in the Organic Superconductors $\mathsf{\kappa}$ -(BEDT-TTF) $\mathsf{_2}$ Cu(NCS) $\mathsf{_2}$ and $\mathsf{\kappa}$ -(BEDT-TTF) $\mathsf{_2}$ Cu[ N(CN) $\mathsf{_2}$ ] Br