Local spectroscopy of carrier reflection at the interface between a normal metal and the Peierls conductor K0.3MoO3

The nature of carrier reflection from a normal metal-Peierls conductor interface is clarified by studying the characteristics of point contacts formed with an intermediate metallic layer sputtered onto the (010) face of K0.3MoO3 crystals (injection along the chains) or the ( 201) face (injection perpendicular to the chains). In the Peierls state, for bias voltages eV smaller than the Peierls gap ΔP, an excess differential resistance is observed with a local minimum at V=0. The magnitude of the excess resistance is proportional to a 2/d 2, where a is the contact diameter and d is the thickness of the metal film. The excess resistance is much higher for injection along the chains than for injection perpendicular to them. A comparative analysis of the data for different injection directions indicates that the dominant contribution to the excess resistance for injection along the chains is from normal reflection of carriers without changes in the sign of their charge and with a momentum transfer 2p F to the condensate of electron-hole pairs carried away from the interface.