Cryogenic STM & SFM

Low Temperature 3He & 4He SPM Operation in High Magnetic Fields

At a Glance

  • Scanning Tunneling Microscopy and –Spectroscopy
  • Spin Polarized Tunneling Microscopy and –Spectroscopy
  • Inelastic Tunneling Spectroscopy
  • Scanning Force Microscopy and -Spectroscopy
  • Magnetic Force Microscopy / Magnetic Exchange Force Microscopy
  • Electrostatic Force Microscopy / Kelvin Probe
  • Atom Manipulation
  • Temperature Variation
  • Magnetic Field Variation (Single Axis, 2D- or 3D Vector Field)
Top

Bottom Loader Concept

The system concept is based on a bottom loader cryostat from Oxford Instruments with various magnet configurations and two alternative cooling techniques: a pumped 4He variable temperature insert for continuous STM operation from 2.5 K up to 300 K and a 3He insert for temperatures below 500 mK.
Two different microscopes are available: a Cryogenic STM for ultimate STM/STS performance and an interferometer-based Cryogenic SFM for AFM, STM, and MFM measurements. Using a rigid vertical manipulator, the cryostat insert with attached microscope can be transferred to the STM chamber for in-situ tip/sample exchange (situated below the cryostat). A second custom-tailored chamber with a fast entry load lock serves for sample preparation purposes and additional analysis techniques.

Top

Proven Performance

High-performance SPM operation at low temperatures and high magnetic fields puts stringent requirements on instrument design. With the Cryogenic series, Omicron has developed a stable and multifunctional platform for delicate experimental conditions.

Furthermore, the reduced surface diffusion allows for atom manipulation including measurements of the involved forces and the systematic study of the adsorption behavior of selected atoms and molecules.

These properties of a low temperature SPM system in combination with high magnetic fields open up the access to a larger variety of measurements like Magnetic Force Microscopy, Magnetic Exchange Force Microscopy or Spin Polarized Scanning Tunneling Micro-scopy and –Spectroscopy.

SPM operation at cryogenic temperatures is a well-established technique and known to be key to observation of topography and electronic structure of atoms, clusters, molecules, islands and surfaces in general. A small lateral and vertical drift as well as the reduced thermal energy broadening of the local density of states at low temperatures are ideal pre-conditions for long term spectroscopy experiments.

Top