Anisotropy of Upper Critical Field in a One-Dimensional Organic System, (TMTTF)(2)PF6 under High Pressure

作者：Kano Mika^*; Mori Hatsumi; Matsubayashi Kazuyuki; Itoi Miho; Hedo Masato; Murphy Timothy P; Tozer Stanley W; Uwatoko Yoshiya; Nakamura Toshikazu

来源：Journal of the Physical Society of Japan, 2012, 81(2): 024716.

DOI：10.1143/JPSJ.81.024716

• superconductivity
• TMTTF
• quasi one-dimensional conductor
• organic superconductor
• high pressure
• upper critical magnetic field
• GL coherence length

We have measured the temperature-dependent resistivity of (TMTTF)(2)PF6 up to 7 GPa using a turnbuckle-type diamond anvil cell (DAC) and at magnetic fields of up to 5 T. Unlike previous reports on organic compounds, a zero resistance was observed in the superconducting state even at high pressures. Superconductivity was observed in the range of P = 4.18 to 6.03 GPa and showed a peak T-c of 2.25K at 4.58 GPa. The temperature dependence of the upper critical magnetic field H-c2(T) was determined via resistivity at P = 4.58 GPa, for the intrachain (a), interchain (b%26apos;), and interlayer (c*) configurations, and H-c2(T) displays a positive curvature without saturation. This could be related to the wide pressure range of the coexistence between the spin density wave (SDW) and superconductivity (SC) ground state, and may be caused by an FFLO state, for a magnetic field along the a- and b%26apos;-axes with T %26gt;= 0: 5K for P = 4.48 GPa. This feature is suppressed with increasing pressure when the orbital pair breaking mechanism becomes dominant. The Ginzburg-Landau coherence lengths for three different axes obtained from this work show that (TMTTF)(2)PF6 is an anisotropic three-dimensional superconductor.

• 出版日期2012-2