A research group led by Professor Masaaki Tanaka and Associate Professor Le Duc Anh of the Graduate School of Engineering has developed a technique to form high-quality, arbitrarily shaped superconducting β-Sn metal at any position on a topological Dirac semimetal α-Sn thin film by laser irradiation, creating an atomically flat α-Sn/β-Sn planar heterostructure. The α-Sn region exposed to the focused laser undergoes a phase transition to β-Sn due to heat, exhibiting superconductivity with a critical temperature of 3.7 K. In the β-Sn nanowire structures fabricated within the α-Sn thin film, a superconducting diode effect was observed: the state switched between superconducting and normal conducting depending on the current direction, even at zero magnetic field. Furthermore, applying a magnetic field achieved a maximum rectification ratio of 10.8%. Forming high-quality interfaces between topological materials and superconductors has been a challenging task in quantum device development. This achievement resolves that difficulty, providing a simple, low-cost processing method suitable for large-area and mass production. The research paper was published in the online edition of Advanced Materials on March 3rd.
[Link]