Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 40: Methods: Scanning probe techniques I
O 40.6: Vortrag
Mittwoch, 25. März 2009, 16:15–16:30, SCH A316
A low-temperature high resolution scanning tunneling microscope with a three-dimensional magnetic vector field operating in ultra-high vacuum — •Marco Pratzer, Torge Mashoff, and Markus Morgenstern — II. Institute of Physics B, Otto-Blumenthal-Straße, RWTH Aachen and JARA-FIT, 52074 Aachen
Scanning tunneling microscopy and spectroscopy at low temperatures lead to a detailed microscopic understanding of electronic interactions. The combination of a low-temperature spin-polarized STM with a rotatable magnetic vector field, in addition, allows to determine the full map of magnetic anisotropies for individual nano-entities. Moreover, complex noncollinear spin structures of nanoclusters could be mapped by appropriately aligning the relative magnetization axis of probe and sample with the help of the external fields.
We present a low-temperature ultra-high vacuum scanning tunneling microscope setup with a combination of a superconducting solenoid coil and two split-pair magnets, providing a rotatable magnetic field of 500 mT applicable in all spatial directions. An absolute field maximum of B=7 T (3 T) can be applied perpendicular (parallel) to the sample surface. The instrument is operated at a temperature of 5 K. Topographic and spectroscopic measurements on tungsten carbide and indium antimonide revealed a z-noise of 600 fmpp even in magnetic field. The energy resolution is, at least, below 6.5 meV. In addition the microscope is equipped with a tip exchange mechanism and a lateral sample positioning stage.