A Joule–Thomson low-temperature scanning tunneling microscope with vector magnet and rotatable scanning head

We present a Joule-Thomson (JT) cooled scanning tunneling microscope (STM) integrated with a two-axis vector magnet, designed for frontier investigations into low dimensional condensed matter physics. Distinct from previously developed STM systems, the present design realizes three-dimensional magnetic field manipulation through a piezoelectrically rotatable STM head combined with a standard commercial two-axis superconducting magnet (8 T out-of-plane and 2 T in-plane), while maintaining a bottom-loading architecture with optical accessibility. Via a dual-dewar architecture and JT refrigeration, the STM system achieves a base temperature of 1.2 K with minimal cryogen consumption. The system is operated in an ultrahigh vacuum environment combined with molecular beam epitaxy, supporting a diverse range of samples from in situ grown nanostructures to cleaved bulk crystals. Performance characterization validates atomic-resolution imaging stability, alongside high-resolution tunneling spectroscopy measurements. The STM system is also compatible for performing tuning-fork atomic force microscopy, transport measurements, as well as future upgrade to dilution refrigeration.