Lichen Ji (Tsinghua U) - Inverse Proximity Effect and Unconventional Superconductivity in Superconductor/Ferromagnet Hybrids

ABSTRACT

Two-dimensional (2D) heterostructures represent one of the most significant applications of 2D materials, offering a platform to explore novel quantum phenomena. In particular, hybrid thin films composed of superconductors (S) and ferromagnets (F) exhibit a rich interplay of competing orders at their interface, giving rise to exotic states such as triplet pairing and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. Despite extensive experimental and theoretical efforts, many fundamental questions remain open, and systematic studies integrating both microscopic and macroscopic approaches to investigate unconventional superconductivity in S/F hybrids are still lacking.

We conducted a systematic study of molecular beam epitaxial 2D vertical S/F hybrids consisting of superconducting lead layers and ferromagnetic CrTe layers using in situ scanning tunneling microscopy and ex situ transport measurements. Our findings reveal an unconventional superconducting gap structure and a strong inverse proximity effect. Transport measurements further demonstrate a significant suppression of both the critical temperature and upper critical field. Additionally, we observe an oscillatory dependence of the critical temperature on the CrTe layer thickness and a superconducting re-entrant behavior within a specific range of external magnetic fields, providing compelling evidence for FFLO states in Pb/CrTe hybrid thin films. These results offer new insights into the unconventional superconducting properties of Pb/CrTe hybrids, underscoring the crucial role of interfacial effect and inverse proximity effect in modulating their superconducting behavior.

https://eu02web.zoom-x.de/j/67910291283?pwd=TzNDaHViY2dBYjNpSUhwUzZDcHEvZz09

Meeting-ID: 679 1029 1283

Access Code: 01187