STM spectroscopy of (MDT-TTF) 2AuI 2

Abstract

The electron tunneling was performed on the superconducting phase of (MDT-TTF) 2AuI 2 using STM. The tunneling differential conductance at T=1.4 K shows the superconducting energy gap structure clearly. The conductance near zero bias voltage is well reduced while the enhancement at the gap edge is observed. The obtained gap Δ 0=2 meV (2 Δ 0/k T c=12) is larger than that of the weak coupling limit. The shape of the spectrum, which is different from the BCS density of states, suggests the gap anisotropy. The tunneling spectrum is explained by the d-wave. The conductance well above T c is flat. On the other hand, the pseudo gap like structre is obseved near T c.