Scanning Field Emission Microscopy with Polarization Analysis (SFEMPA)

Abstract

In the Fowler-Nordheim regime of Scanning Tunneling Microscopy (STM) the tip-target distance is few nanometers to few tens of nanometers. In this situation the tunneling between tip and target is completely suppressed. Instead, electrons can be field-emitted from the tip and their impact with the target might excite electrons off the surface. Under certain circumstances, the excited electrons escape the tip-target junction and build a new electronic system, absent in the tunneling regime of STM. A recent experiment discovered that this electronic system is spin polarized at nanoscale tip-target distances. Here we provide a comprehensive review of all strategies that have been adopted to perform the spin polarized experiments in the Fowler-Nordheim regime of STM. We also present new data that complement the proof of spin polarization and specifically underline the magnetic imaging potential of this new technology, which we call Scanning Field Emission Microscopy with Polarization Analysis (SFEMPA).