Spin polarized scanning tunneling microscopy with EuS coated W tip

Various kinds of ferromagnetic or antiferromagnetic tips have been used to measure local magnetic properties of surfaces in spin polarized scanning tunneling microscopy technique. In this study, europium sulfide (EuS) coated tungsten tip is used because EuS coated tip is known to have a Sherman factor of 0.85 due to its exchange splitting [1,2]. With this tip, we have imaged different magnetic domains on iron islands grown on W(110) surface. The differential conductance was mapped at liquid helium temperature because Curie temperature of EuS is 16K. We were able to manipulate the magnetization orientation of a ferromagnetic domain of Fe island by spin polarized tunneling current. We measured magnetic properties of single-layer FeSe film on SrTiO₃ to confirm a theory that predicted antiferromagnetic order on Fe layer in the film.

[1] N. Müller, W. Eckstein, W. Heiland, and W. Zinn, Phys. Rev. Lett. 29, 1651 (1972)
[2] J. Stöhr, H. C. Siegmann, Magnetism: From Fundamentals to Nanoscale Dynamics, Springer (2006)