Scanning Tunneling Microscopy and Spectroscopy of UTe₂

Recent findings strongly indicate that UTe₂ behaves as a heavy-fermion superconductor displaying traits of a spin-triplet p-wave superconductor, positioning it as an excellent candidate for investigating topological superconductivity. A scanning tunnelling microscopy study previously revealed unusual charge density wave (CDW) and pair density wave (PDW) formations in UTe₂^1-2. In our research, we employed both normal tungsten (W) and superconducting niobium (Nb) tips to expand our understanding of topological superconductors such as UTe₂ through scanning tunneling microscopy and spectroscopy (STM/S). We found that UTe₂ can be cleaved along different orientation planes, including (0-11) and (001), as well as by U and Te surface terminations, employing STM/S techniques. When using the superconducting Nb tip, we observed a robust zero-bias peak on the (0-11) crystal termination of UTe₂ in conductance measurements. Furthermore, our study revealed that the atomic step edge of UTe₂ enhances the zero-bias conductance peak (ZBCP), while the U-terminated terrace lacks a ZBCP entirely.

1. Aishwarya, A. et al. Magnetic-field-sensitive charge density waves in the superconductor UTe₂. Nature 618, 928–933 (2023).

2. Gu, Q. et al. Detection of a pair density wave state in UTe₂. Nature 618, 921–927 (2023).