Facilities of CRYOHALL and their use according to functionality
Sub mK research facilities
The two nuclear demagnetization cryostats of LTL are specialized pieces of equipment which are the flagships of LTL in the Microkelvin project. One of them is used for studies of superfluid 3He in collaboration with researchers from all over Europe, Japan, and Russia. The second one is employed for unique cooling experiments trying to find new superfluid systems in collaboration with researchers from UK and Russia.
Sub 1K research facilities
Altogether eight dilution refrigerators provide the backbone of the low temperature nanophysics research in the CRYOHALL. These refrigerators typically provide a 20-30 mK base temperature, which is enough for studies of phase coherent, even ballistic transport in nanostructures and for quantum information processing in superconducting quantum circuits. The dilution refrigerators are in frequent use within the Microkelvin program as well as in many other projects with European funding (CARDEQ, ENTS, GEOMDISS, RODIN, SCOPE). One more refrigerator is under construction within the TEKES-funded FinCryo-project which develops pulse-tube based dilution refrigerator technology. The final goal of the project is to build a prototype refrigerator of top-loading type and to commercialize the product.
Research facilities at liquid helium temperatures
In the range of temperatures 4.2 – 1.2 K, LTL has lots for cryostats with different measurement capabilities, ranging from simple DC electrical measurements to involved microwave measurements for noise, cross-correlations, and vibrations in NEMS resonators. These facilities are important for small companies as well as to VTT researchers working in cryogenic applications (Aivon, Nanoway, Picowatt, Elekta Neuromag) since the available cryostats allow these CRYOHALL users to quickly try their ideas in cryogenic environment. The CRYOHALL also operates a SQUID magnetometer (owned by the Dept. of Applied Physics) which is used by several external researchers.
Room temperature research facilities
Room temperature research facilities are used to characterize samples after fabrication. The equipment include a microRaman setup for local Raman measurements and an atomic force microscope. Using the AFM, surface enhanced Raman can be investigated. In addition, there are setups to measure susceptibility of novel materials at microwave frequencies. These systems are essential for the industrial people who collaborate with the CRYOHALL researchers on materials issues, for example, on graphene and nanotubes. These setups are also in frequent use by material scientists from other laboratories of the Aalto University.
Fabrication and testing facilities
The facilities include a production line for e-beam lithography down to 100 nm resolution, operated in a semi-clean-room environment. The facilities are sufficient for basic samples in mesoscopic physics and for nanocarbon devices. The nanofabrication facilities of LTL supplement the infrastructure at Micronova in the sense that cleanliness requirements are not as strict, and more non-standard operations are allowed, and even modifications on the facilities are possible in order to reach the research goals. In this adaptable way the CRYOHALL infrastructure can serve the Microkelvin users whose needs are often different from the standard ones provided by Micronova. The semi-clean-room environment also serves many researchers of Aalto University in their work on nanocarbons. More-over, the fabrication facilities include equipment for heat treatment, critical point drying, and annealing in order to guarantee the best quality of samples before cool down to mK temperatures.
Reservation of Cryohall Installations
- ROTA, Rotating cryostat (140uK 3He sample temperature, room 170a), (ROTA Cryostat photos)
- uKI, Stationary cryostat (50µK base temperature, room 170a), (uKI Cryostat photos)
- NANO-1 (NANO-RF), Cryostat with 20mK base temperature (room 154a)]
- NANO-2 (NANO-X), Cryostat with 20mK base temperature (room 154e)
- PICO-3 (PICO_DRY) Cryostat with 20mK base temperature (room 154b)
- KVANTTI-1, Cryostat with 20mK base temperature (room 154f)