title: A 10 mK scanning tunneling microscope operating in ultra high vacuum and high magnetic fields.
abstract: We present design and performance of a scanning tunneling microscope (STM) that operates at temperatures down to 10 mK providing ultimate energy resolution on the atomic scale. The STM is attached to a dilution refrigerator with direct access to an ultra high vacuum chamber allowing in situ sample preparation. High magnetic fields of up to 14 T perpendicular and up to 0.5 T parallel to the sample surface can be applied. Temperature sensors mounted directly at the tip and sample position verified the base temperature within a small error margin. Using a superconducting Al tip and a metallic Cu(111) sample, we determined an effective temperature of 38 ± 1 mK from the thermal broadening observed in the tunneling spectra. This results in an upper limit for the energy resolution of ΔE = 3.5 kBT = 11.4 ± 0.3 μeV. The stability between tip and sample is 4 pm at a temperature of 15 mK as demonstrated by topography measurements on a Cu(111) surface.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Assig
authors.forename: Markus
authors.initials: M
authors.lastname: Etzkorn
authors.forename: Axel
authors.initials: A
authors.lastname: Enders
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Stiepany
authors.forename: Christian R
authors.initials: CR
authors.lastname: Ast
authors.forename: Klaus
authors.initials: K
authors.lastname: Kern