Integrating STM with Cryogen-Free Systems for Enhanced Stability in Harsh Conditions

Scanning tunneling microscopy (STM) achieves atomic-level imaging, vital for advancements in physics and materials science. Conducting spectroscopy and imaging at low temperatures with magnetic fields is complex, further complicated in cryogen-free systems by noise and vibrations from cryogenic equipment. We successfully integrated a compact STM with a cryogen-free superconducting magnet. The STM head features a simple design with single piezoelectric tube (PT) and a piezoelectric shaft (PS) secured by a CuBe spring strip. The PS is used as a coarse approach mechanism inside the scanning tube, integrated for the first time with a cryogen-free superconducting magnet. STM long term stability were confirmed by achieving minimal drift rates of 3.5 pm/min in the X–Y plane and 4.1 pm/min along the Z-axis at 1.8 K. Experiments were also conducted with magnetic fields ranging from 0 T to 9 T at 300 K, which yielded high-quality atomic-resolution images of graphite sample. Additionally, the atomic-resolution imaging and dI/dV spectra of the NbSe₂ surface at low temperature further validate the STM's exceptional performance in high-resolution imaging and scanning tunneling spectroscopy (STS) measurements. These results highlight the STM’s exceptional stability, resistance to vibration, and reliable performance in high magnetic fields and low temperature. This compact STM design holds significant promise for developing a rotatable STM capable of operating in ultra-high magnetic fields, ideal for investigating the anisotropic properties of material’s electronic structures.