Phonon structure of LaB6 by point-contact spectroscopy

Article abstract of DOI:10.1143/JPSJ.57.361

The differential resistance dV/dI versus voltage characteristics is studied for point-contacts between a LaB₆-needle on one side and a LaB ₆ (100)-cleavage surface on the other. A technique of automatic in situ cleaning is used to clean the sample surface. The spectra of pure metal point-contacts are contrary to that of the tunneling contacts interposed by the oxide layer, that is, the former is for the barrierless junction of enough clean surface and the latter is for the barrier-type junction of intentionally oxidized surface. The measurements of the second derivative d ²K/dI² give the information on the phonon density of states of LaB₆, adding new experimental results on the current neutron scattering experiment. The peaks of the phonon density of states of LaB₆ are situated at 12, 24, 38 and 50 meV.