Abstract
We present the design and performance of a cryogenic scanning tunneling microscope (STM) which operates inside a water-cooled Bitter magnet, which can attain a magnetic field of up to 38 T. Due to the high vibration environment generated by the magnet cooling water, a uniquely designed STM and a vibration damping system are required. The STM scan head is designed to be as compact and rigid as possible, to minimize the effect of vibrational noise as well as fit the size constraints of the Bitter magnet. The STM uses a differential screw mechanism for coarse tip-sample approach, and operates in helium exchange gas at cryogenic temperatures. The reliability and performance of the STM are demonstrated through topographic imaging and scanning tunneling spectroscopy on highly oriented pyrolytic graphite at T = 4.2 K and in magnetic fields up to 34 T.
Highlights
A Scanning Tunneling Microscope (STM) allows sample surfaces to be imaged with sub-nanometer topographic resolution and enables local density of states to be directly probed via Scanning Tunneling Spectroscopy (STS).1–3 scanning tunneling microscope (STM)/STS at cryogenic temperatures and in magnetic fields have become crucial tools in condensed matter physics, enabling the study of unique physical phenomena such as atomic nanomagnets,4,5 surface states in topological insulators,6 and Landau quantization in low-dimensional electron systems.7–11 Up to now, low temperature STM/STS in magnetic fields has been limited to a magnetic field strength of 18 T,12,13 as the majority of designs have been based on superconductor magnets
We present the design and performance of a cryogenic scanning tunneling microscope (STM) which operates inside a water-cooled Bitter magnet, which can attain a magnetic field of up to 38 T
We have presented the design and characteristics of a scanning tunneling microscope, designed for cryogenic operation in a 38 T resistive Bitter magnet
Summary
A Scanning Tunneling Microscope (STM) allows sample surfaces to be imaged with sub-nanometer topographic resolution and enables local density of states to be directly probed via Scanning Tunneling Spectroscopy (STS). STM/STS at cryogenic temperatures and in magnetic fields have become crucial tools in condensed matter physics, enabling the study of unique physical phenomena such as atomic nanomagnets, surface states in topological insulators, and Landau quantization in low-dimensional electron systems. Up to now, low temperature STM/STS in magnetic fields has been limited to a magnetic field strength of 18 T,12,13 as the majority of designs have been based on superconductor magnets. STM/STS at cryogenic temperatures and in magnetic fields have become crucial tools in condensed matter physics, enabling the study of unique physical phenomena such as atomic nanomagnets, surface states in topological insulators, and Landau quantization in low-dimensional electron systems.. Low temperature STM/STS in magnetic fields has been limited to a magnetic field strength of 18 T,12,13 as the majority of designs have been based on superconductor magnets. While the authors describe an STM which is operational in magnetic fields up to 27 T, the instrument cannot operate at cryogenic temperatures, severely limiting its application for high resolution STS. We present a specially designed STM capable of operating at cryogenic temperatures in a resistive Bitter magnet at the High Field Magnet Laboratory (HFML) in Nijmegen. We observe a series of peaks in dI/dV in high magnetic fields, which we attribute to Landau quantization of decoupled graphene as well as graphite
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