Electron-spin-resonance STM on iron atoms in silicon

Electron-spin-resonance-scanning tunneling microscopy (ESR)-(STM) of iron a toms in silicon was observed: Si(111) surfaces were covered with iron atoms and annealed. This gives surfaces covered with small islands of different silicide phases. We could detect an ESR-STM signal that corresponds to a g value of 2.07. The signal was split by magnetic field modulation, and phase -sensitive detection was applied. This shows that electron-spin-resonance ( ESR)-STM signals can be detected on a surface that is imaged with atomic re solution and that it is possible to observe a g not equal 2 spin center. Ge tting absorption (instead of the expected derivative) Line shapes with phas e-sensitive detection is explained by the asymmetry in the line shape, whic h is a result of a rapid scan of the signal. Then, when the integration tim e of the phase sensitive detector is close to the time it takes to sweep th e linewidth of the signal, absorption line shapes are observed.