The laboratory provides an extensive set of tools and equipment for studying ultrafast phenomena in complex systems on the nanometer scale at temperatures down to 4.2 K. Combining the power of low-temperature multiprobe scanning tunnelling microscopy with femtosecond laser excitation, we are developing the methods for investigating microscopic dynamics on all time scales ranging from femtosecond to minutes or hours.
Location: Room C 010
Scanning tunnelling microscopy
The lab is equipped with the low-temperature 4-probe STM (“LT Nanoprobe”), which, beyond the standard STM/STS capabilities, features fully independent control of all 4 STM tips, their precise positioning using the built-in SEM microscope, the possibility of Q+ AFM. The system has optical access and can be coupled with the femtosecond laser system for studying photoinduced effects.
The system operates in the temperature range between 4.2 and 300 K and at the base pressure of ~3e-11 mB. It is additionally equipped with tools for in-situ sample storing, exfoliation and processing. Additionally, the system is compatible with the UHV Suitcase for direct transferring of samples between different vacuum systems without exposing them to air.
The special 2-beam optical setup provides the ability to excite samples inside the STM chamber with ultra-short laser pulses at 800 nm, 400 nm or in the THz range (with the peak at ~1 THz) (and their combination with an optional time delay). The setup is equipped with an active beam stabilization ensuring a precise positioning on the scanned sample.
The combination of the ultra-short laser pulses with the STM allows studying of the metastable phenomena observed in conventional optical experiments with atomic resolution.
The special high-voltage electronics in combination with high-sensitivity tunnelling current measurement allow expanding traditional slow STM measurements into the millisecond or microsecond range, ensuring faster dynamics can be captured with atomic precision. The Fast STM module provides framerates of more than 10 Hz.
The STM optical setup and custom in-house scanning probe designs allow coupling of the ultrafast laser pulses with the tunnelling tips for optical pump – STM probe experiments with picosecond time resolution. With this method, the dynamics in the material can be probed with the usual all-optical pump-probe technique.
UHV Suitcase for sample transfer
The UHV Suitcase allows a simultaneous transfer of up to 6 samples between different UHV and HV systems without exposing them to the atmosphere. The pressure inside is kept at the level of under 1e-9 mB with an active ion pump and a passive non-evaporative getter. The latter allows keeping the samples at suitable conditions for hours during the transfer.
With a custom-designed compact HV chamber, the samples can be transferred from the UHV conditions in the suitcase to an oxygen-free (inert) atmosphere inside a glovebox.