Low-temperature equipment

Janis top-loading Helium-3 Cryostat (<300 mK) with sample in UHV – for atomic resolution STM

August 8, 2014

The Janis Research ultra-low temperature (ULT) group is proud to announce the development of an enhanced top-loading Helium-3 cryostat with sample in UHV environment, the model HE-3-TLSUHV-STM.

Woburn, Massachusetts, USA – August 7, 2014 – This ULT system is optimized for atomic resolution STM measurements, and can be integrated with a commercially supplied or user-built STM. A central UHV tube (32 mm diameter or larger) and gate valve provide top-loading access to the low temperature, high magnetic field region for sample and tip exchange. Vertical, horizontal, and 2D/3D vector field superconducting magnets are available and fully integrated.

ULT STM systems are frequently used to investigate the electronic and magnetic properties of materials. Applications include quantum computing and information, future electronics, and nanoscale manufacturing. A ULT STM system can be used to observe or manipulate the topography and electronic structures of atoms, islands, molecules, and surfaces. Techniques such as magnetic force microscopy (MFM) and spin polarized STM can be used to investigate a variety of materials, in conjunction with variable temperature and magnetic field conditions. Typical materials studied include metals, semiconductors, thin films, and carbons such as graphene and carbon nanotubes.

The Janis HE-3-TLSUHV-STM provides operating time of >80 hours at a base temperature of <300 mK; longer operating times are also possible by using additional He-3 gas. Quiet operation is assured through the use of proprietary acoustic noise reduction features inside the 1 K pot, and vibration reducing mechanical support structure on the He-3 pot; it is also possible to operate the system without pumping on the 1 K pot for further vibration reduction. The system includes a mechanical heat switch for rapid precooling, and also includes cooled 4 K and 1.5 K radiation shutters for maximum hold time and minimum base temperature. Other available features include a sliding seal, low and high frequency wiring, and pre-installed optical fibers.

Janis top-loading Helium-3 Cryostatwith sample in UHV – for atomic resolution STM

Distance (nm)

Atomically resolved topographic image of NbSe2 obtained at constant current mode.

Tunneling current = 150 pA, bias voltage = 20 mV, scan speed = 13nm/s.

(Data courtesy of Pratap Raychaudhuri, Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, India. Measurements were made in a non-UHV system.)