Ultralow-temperature atomic force microscopy for the investigation of mesoscopic systems

have developed an atomic force microscope for the study of mesoscopic samples. The microscope operates at milliKelvin temperatures and in high magnetic fields. Sample images are presented showing atomic steps at 4.2 K and a mesoscopic ring at 30 mK in a 9 T field. Deflection of the force-sensing cantilever is detected via an optical fiber interferometer operating at very low power levels. The microscope is well suited to surface imaging simultaneous with transport measurements at ultralow temperatures, and to the in situ manipulation of sample properties. (C) 1998 American Institute of Physics.