Development of an ultrahigh vacuum scanning tunneling microscope cooled by superfluid 4He

We have developed an ultrahigh vacuum (UHV) scanning tunneling microscope (STM) cooled by superfluid He-4. This microscope is integrated with a solenoid 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 by obtaining atomic resolution images of Si reconstructed surfaces at low temperatures. The STM performance was unaffected by the application of high magnetic fields. (C) 2001 American Institute of Physics.