Scanning tunneling microscopy and spectroscopy on iron-pnictides

Tremendous excitement has followed the recent discovery of superconductivity up to T-c = 56 K in iron-arsenic based materials (pnictides). This discovery breaks the monopoly on high-T-c superconductivity held by copper-oxides (cuprates) for over two decades and renews hope that high-T-c superconductivity may finally be theoretically understood and widely applied. Since scanning tunneling microscopy (STM) and spectroscopy (STS) have been key tools in the investigation and understanding of both conventional and unconventional superconductivity, these techniques are also applied to the pnictides. While the field is still in its early stages, several important achievements by STM and STS have been reported on the pnictides. In this paper, we will review their contribution towards an understanding of superconductivity in this new class of materials. (C) 2009 Elsevier B.V. All rights reserved.