Tunneling Spectroscopy on Underdoped La2-xSrxCuO4.

We report the results of low-temperature tunneling spectroscopy on underdoped La1.94Sr0.06CuO4 single crystal with Tc = 14 K. The tunneling spectra have been obtained on the ab plane at 4.2 K indicating gap structure with the asymmetric V-shaped background. While we have observed the spectra with gap value Δ consistent with previous ARPES data of the underdoped samples, a few spectra exhibit almost the same magnitude of Δ observed on the optimally doped sample in our former tunneling study. This result suggests the existence of the strong gap inhomogeneity in under doped La2-xSrxCuO4. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]