Diode effect in Josephson junctions with epitaxial trigonal tellurium tunnel barrier

Recently, the nonreciprocal phenomena in superconductors, such as the diode effect of supercurrent, has

gained many interests. Such phenomena, also known as Josephson diode effect (JDE), could be tied to the

broken inversion symmetry and/or broken time reversal symmetry of the superconductor or the barrier

material itself. In this talk, we will demonstrate the fabrication of Josephson junctions with epitaxial

barrier material, i.e. trigonal tellurium, which hosts chiral chains of Te atoms along its c-axis and breaks

inversion symmetry. Based on our prior results in trigonal tellurium tunnel barriers, where evidences of

Andreev bound states and largely enhanced Lande g-factor are observed, we will demonstrate JDE in our

trigonal Te Josephson junction devices grown on epitaxial Nb/Au(111) layers using molecular beam

epitaxy. The trigonal phase is confirmed using both reflective high energy electron diffraction and Raman

spectroscopy. We will further discuss the response of JDE under an applied planar magnetic field, which

varies the Zeeman field.