We present a novel homebuilt scanning tunneling microscope (STM) with atomic resolution integrated into a cryogen-free superconducting magnet system with a variable temperature insert. The STM head is designed as a nested structure of double piezoelectric tubes (PTs), which are connected coaxially through a sapphire frame whose top has a sample stage. A single shaft made of tantalum, with the STM tip on top, is held firmly by a spring strip inside the internal PT. The external PT drives the shaft to the tip–sample junction based on the SpiderDrive principle, and the internal PT completes the subsequent scanning and imaging work. The STM head is simple, compact, and easy to assemble. The excellent performance of the device was demonstrated by obtaining atomic-resolution images of graphite and low drift rates of 30.2 pm/min and 41.4 pm/min in the X–Y plane and Z direction, respectively, at 300K. In addition, we cooled the sample to 1.6 K and took atomic-resolution images of graphite and NbSe₂. Finally, we performed a magnetic field sweep test from 0 T to 9 T at 70 K, obtaining distinct graphite images with atomic resolution under varying magnetic fields. These experiments show our newly developed STM’s high stability, vibration resistance, and immunity to high magnetic fields.

Scanning tunneling microscopes (STMs) that work in ultra-high vacuum and low temperatures are commonly used in condensed matter physics, but an STM that works in a high magnetic field to image chemical molecules and active biomolecules in solution has never been reported. Here, we present a liquid-phase STM for use in a 10 T cryogen-free superconducting magnet. The STM head is mainly constructed with two piezoelectric tubes. A large piezoelectric tube is fixed at the bottom of a tantalum frame to perform large-area imaging. A small piezoelectric tube mounted at the free end of the large one performs high-precision imaging. The imaging area of the large piezoelectric tube is four times that of the small one. The high compactness and rigidity of the STM head make it functional in a cryogen-free superconducting magnet with huge vibrations. The performance of our homebuilt STM was demonstrated by the high-quality, atomic-resolution images of a graphite surface, as well as the low drift rates in the X–Y plane and Z direction. Furthermore, we successfully obtained atomic-resolution images of graphite in solution conditions while sweeping the field from 0 to 10 T, illustrating the new STM’s immunity to magnetic fields. The sub-molecular images of active antibodies and plasmid DNA in solution conditions show the device’s capability of imaging biomolecules. Our STM is suitable for studying chemical molecules and active biomolecules in high magnetic fields.

Magnetic Force Microscopy (MFM) is among the best techniques for examining and assessing local magnetic characteristics in surface structures at scales and sizes. It may be viewed as a unique way to operate atomic force microscopy with a ferromagnetic tip. The enhancement of magnetic signal resolution, the utilization of external fields during measurement, and quantitative data analysis are now the main areas of MFM development. We describe a new structure of MFM design based on a cryogen-free superconducting magnet. The piezoelectric tube (PZT) was implemented with a tip-sample coarse approach called SpiderDrive. The technique uses a magnetic tip on the free end of a piezo-resistive cantilever which oscillates at its resonant frequency. We obtained a high-quality image structure of the magnetic domain of commercial videotape under extreme conditions at 5 K, and a high magnetic field up to 11 T. When such a magnetic field was gradually increased, the domain structure of the videotape did not change much, allowing us to maintain the images in the specific regions to exhibit the performance. In addition, it enabled us to locate the sample region in the order of several hundred nanometers. This system has an extensive range of applications in the exploration of anisotropic magnetic phenomena in topological materials and superconductors.