POLAR SPM Lab: Low Temperature SPM with Unsurpassed Hold Time

September 8th, 2021

The key features include: STM, QPlus® AFM & Spectroscopy; Guaranteed Helium Holding Time: >200 h; Integrated TRIBUS Head; Sample and Tip Temperature T <5 K; Vertical Magnetic Field: B = ±5 T; and Independent Tip and Sample Exchange.

The POLAR UHV SPM is a new Low-Temperature Scanning Probe Microscope (SPM) for the highest resolution STM, QPlus® AFM, and spectroscopy experiments at temperatures ranging from <5 K to 420 K and in magnetic fields of up to 5T. Viewports and closable entry doors in the radiation shields allow for independent tip and sample exchange, optical access, and in-situ evaporation.

The ultra-compact cryostat design delivers exceptional mechanical stiffness, creating superior STM stability. Cryostat hold time is optimised through a series of advanced thermal decoupling stages and thermal radiation shields, designed to provide an extremely low rate of liquid helium (LHe) consumption. With a rate below 1 l/day, the instrument achieves an unsurpassed hold time of >200 hours at <5 K with cryostat refilling.

Many of today’s SPM applications require extremely low noise for detection of very small (<500 fA) tunneling currents (e.g. STS or molecular imaging). In the POLAR SPM, ex-situ signal amplifiers for both STM and QPlus® AFM, combined with dedicated wiring, result in maximum experimental flexibility and the highest achievable S/N ratio.

The accompanying series of images show an example of data measured on a Si(111)7x7 surface at a temperature of 4.6 K. The atomically resolved images have been acquired with very small tunnel current setpoints of 300 fA, 100 fA and 60 fA, illustrating the excellent signal quality achievable with the POLAR XT SPM.