Electrical Resistivity of (TMTTF)₂PF₆under High Pressure

Abstract

We investigated the resistivity of quasi 1D organic conductor (TMTTF) 2 PF 6 under high pressure (P 10 GPa) using a cubic anvil pressure system, which can generate a high quality hydrostatic pressure. We observed a superconducting state of (TMTTF) 2 PF 6 under 4 P 5 GPa. Zero resistivity was observed under 4 P 4.5 GPa for the first time. We will discuss the pressure-induced superconductivity with a P-T phase diagram of (TMTTF) 2 PF 6 .

High pressure study of the organic compound (TMTTF)2BF4

“…The A-coefficient of about 0.5 μΩ cm K −n at the critical pressure, 3.5 GPa, is huge. At the maximum of T c a similar value of A has been found in (TMTTF) 2 PF 6 [18] and an even much higher value in (TMTTF) 2 AsF 6 [17]. In the former compound, at pressures well above the superconducting dome, A decreased by about an order of magnitude.…”

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

“…Zero resistivity was never observed in SC phase in other pressure work using a DAC or Bridgman pressure apparatus. Only measurements with a Cubic Anvil Press which generates highly hydrostatic pressures showed superconductivity with zero resistivity14 indicating that our measurement with a DAC has similar accuracy to Cubic Anvil Press. The SC dome lays at P = 4.18 -6.18 GPa in the P − T phase diagram obtained from this work and the highest transition temperature was T c = 2.25 K. Our data extended the range of temperature and pressure and supplemented the reported P −T phase diagram.Also we have shown the temperature dependence of H c2 of three axis on (TMTTF) 2 PF 6…”

“…Therefore we used the data from resistivity measurements of the same crystal using a Cubic Anvil Press for pressurization for normalizing our data at room temperature. 14 The magnetic field was applied along a, b and c * axis and the temperature dependence of the resistivity was measured over the pressure range of P = 4.37 -5.64 GPa at low temperatures. The orientation of the sample was adjusted by changing the angles of the DAC with respect to the probe when mounting.…”

“…8,9 This shows that the pressures generated in present work are as hydrostatic as those of a cubic anvil press which was the only pressure apparatus that allowed zero resistance to be observed in this material. 14 The finite width of the SC transition is considered a fluctuation effect in a low dimensional system. The fluctuation effect associated with transitions cannot be ignored in low dimensional systems, the superconductivity is destroyed in finite temperature and it produces a finite resistance.…”

“…Hump structures seen below T c have not been observed in earlier works. 8,9,14 We consider that these are attributed to an inhomogeneous SC state which may be due to microcracks related to the extreme sample brittleness, and not intrinsic property.…”