Theoretical study of the role of the tip in enhancing the sensitivity of   differential conductance tunneling spectroscopy on magnetic surfaces
  Based on a simple model for spin-polarized scanning tunneling spectroscopy (SP-STS) we study how tip magnetization and electronic structure affects the differential conductance (dI/dV) tunneling spectrum of an Fe(001) surface. We take into account energy dependence of the vacuum decay of electron states, and tip electronic structure either using an ideal model or based on ab initio electronic structure calculation. In the STS approach, topographic and magnetic contributions to dI/dV can clearly be distinguished and analyzed separately. Our results suggest that the sensitivity of STS on a magnetic sample can be tuned and even enhanced by choosing the appropriate magnetic tip and bias setpoint, and the effect is governed by the effective spin-polarization. 
Kriszti\'an Palot\'as, Werner A. Hofer, and L\'aszl\'o Szunyogh
cond-mat.mes-hall cond-mat.mtrl-sci physics.comp-ph