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Robust superconducting state in the low-quasiparticle-density organic metals β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y: Superconductivity due to proximity to a charge-ordered state

Bangura, AF, Coldea, AI, Ardavan, A, Singleton, J, Akutsu-Sato, A, Akutsu, H, Turner, SS, Day, P, Yamamoto, T and Yakushi, K (2005) Robust superconducting state in the low-quasiparticle-density organic metals β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y: Superconductivity due to proximity to a charge-ordered state Physical Review B - Condensed Matter and Materials Physics, 72 (1).

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Abstract

We report magnetotransport measurements on the quasi-two-dimensional charge-transfer salts β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y, with Y=C6H5NO2 and C6H5CN using magnetic fields of up to 45 T and temperatures down to 0.5 K. A surprisingly robust superconducting state with an in-plane upper critical field Bc2 33T, comparable to the highest critical field of any BEDT-TTF superconductor, and critical temperature Tcâ 7K is observed when M=Ga and Y=C6H5NO2. The presence of magnetic M ions reduces the in-plane upper critical field to 18T for M=Cr and Y=C6H5NO2 and M=Fe and Y=C6H5CN. Prominent Shubnikov-de Haas oscillations are observed at low temperatures and high magnetic fields, showing that the superconducting salts possess Fermi surfaces with one or two small quasi-two-dimensional pockets, their total area comprising 6% of the room-temperature Brillouin zone; the quasiparticle effective masses were found to be enhanced when the ion M was magnetic (Fe or Cr). The low effective masses and quasiparticle densities, and the systematic variation of the properties of the β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y salts with unit-cell volume points to the possibility of a superconducting groundstate with a charge-fluctuation-mediated superconductivity mechanism such as that proposed by Merino and McKenzie [Phys. Rev. Lett. 87, 237002 (2001)], rather than the spin-fluctuation mechanism appropriate for the κ-(BEDT-TTF)2X salts. © 2005 The American Physical Society.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Chemistry
Authors :
AuthorsEmailORCID
Bangura, AFUNSPECIFIEDUNSPECIFIED
Coldea, AIUNSPECIFIEDUNSPECIFIED
Ardavan, AUNSPECIFIEDUNSPECIFIED
Singleton, JUNSPECIFIEDUNSPECIFIED
Akutsu-Sato, AUNSPECIFIEDUNSPECIFIED
Akutsu, HUNSPECIFIEDUNSPECIFIED
Turner, SSUNSPECIFIEDUNSPECIFIED
Day, PUNSPECIFIEDUNSPECIFIED
Yamamoto, TUNSPECIFIEDUNSPECIFIED
Yakushi, KUNSPECIFIEDUNSPECIFIED
Date : 2005
Identification Number : 10.1103/PhysRevB.72.014543
Additional Information : Copyright 2005 The American Physical Society.
Depositing User : Symplectic Elements
Date Deposited : 27 Sep 2013 17:16
Last Modified : 09 Jun 2014 13:12
URI: http://epubs.surrey.ac.uk/id/eprint/802899

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