Modifying the surface electronic properties of YBa2Cu3O7-delta with cryogenic scanning probe microscopy

TL;DR

This study demonstrates how cryogenic scanning probe microscopy can locally modify and probe the electronic surface properties of YBa2Cu3O7-delta, revealing reversible surface charging and defect layers.

Contribution

It introduces a cryogenic STM method to modify and analyze the surface electronic properties of YBa2Cu3O7-delta at a local scale, highlighting reversible surface charging effects.

Findings

Negative bias modifies local conductance of the surface layer.

Effect disappears after etching away the degraded layer.

Reversible surface charging indicates defect layers even on pristine surfaces.

Abstract

We report the results of a cryogenic study of the modification of YBa2Cu3O7-delta surface electronic properties with the probe of a scanning tunneling microscope (STM). A negative voltage applied to the sample during STM tunneling is found to modify locally the conductance of the native degraded surface layer. When the degraded layer is removed by etching, the effect disappears. An additional surface effect is identified using Scanning Kelvin Probe Microscopy in combination with STM. We observe reversible surface charging for both etched and unetched samples, indicating the presence of a defect layer even on a surface never exposed to air.