Development of an ultrahigh vacuum scanning tunneling microscope cooled bysuperfluid He-4

We have developed an ultrahigh vacuum (UHV) scanning tunneling microscope ( STM) cooled by superfluid He-4. This microscope is integrated with a soleno id and split-pair superconducting magnet. The STM can be operated at 300 >T >4 K in a rotatable magnetic field of up to 8 T perpendicular to, and 1.5 T parallel to the sample surface. Moreover, tips and samples may be changed without venting the UHV system. The performance of the STM was confirmed b y obtaining atomic resolution images of Si reconstructed surfaces at low te mperatures. The STM performance was unaffected by the application of high m agnetic fields. (C) 2001 American Institute of Physics.