Eur. Phys. J. B 25, 319-331 (2002)
https://doi.org/10.1140/epjb/e20020037

Coexistence of superconductivity and spin density wave orderings in the organic superconductor (TMTSF)₂PF₆

¹ Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France
² Institut za fiziku, p.p. 304, 10001 Zagreb, Croatia
³ Dept. of Condensed Matter Physics and Chemistry, Risø National Laboratory, 4000 Roskilde, Denmark

Corresponding author: ^a tvuletic@ifs.hr

Received: 3 September 2001
Revised: 9 November 2001
Published online: 15 February 2002

Abstract

The phase diagram of the organic superconductor (TMTSF)₂PF₆ has been revisited using transport measurements with an improved control of the applied pressure. We have found a 0.8 kbar wide pressure domain below the critical point (9.43 kbar, 1.2 K) for the stabilisation of the superconducting ground state featuring a coexistence regime between spin density wave (SDW) and superconductivity (SC). The inhomogeneous character of the said pressure domain is supported by the analysis of the resistivity between and and the superconducting critical current. The onset temperature is practically constant ( K) in this region where only the SC/SDW domain proportion below is increasing under pressure. An homogeneous superconducting state is recovered above the critical pressure with falling at increasing pressure. We propose a model comparing the free energy of a phase exhibiting a segregation between SDW and SC domains and the free energy of homogeneous phases which explains fairly well our experimental findings.