Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Superconductivity: Properties and Electronic Structure II
TT 16.1: Talk
Tuesday, March 18, 2025, 09:30–09:45, H32
Layer-thickness and substrate effects on superconductivity in epitaxial FeSe films on BLG/SiC(0001) — •yongsong wang1, haojie guo1, ane etxebarria2, sandra sajan1, sara barja1,2,3,4, and miguel moreno ugeda1,3,4 — 1Donostia International Physics Center, San Sebastián, Spain — 2Department of Polymers and Advanced Materials, University of the Basque Country, San Sebastián, Spain — 3Centro de Física de Materiales, San Sebastián, Spain — 4Ikerbasque, Basque Foundation for Science, Bilbao, Spain
The layered nature and simple structure of FeSe reveal this iron-based superconductor as a unique building block for the design of artificial heterostructure materials. While superconductivity develops in ultrathin films of FeSe on SrTiO3 substrates, it remains unclear whether it can be developed on more chemically inert, layered materials such as graphene. Here, we report on the characterization of the structural, chemical and electronic properties of few-layer FeSe on bilayer graphene grown on SiC using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS). STM imaging of our FeSe films with thicknesses up to three layers exhibit the tetragonal crystal structure of bulk FeSe, which is supported by XPS spectra consistent with the FeSe bulk counterpart. While our STS measurements at 340 mK reveal a metallic character for few-layer FeSe on BLG/SiC, they show an absence of superconductivity, as the low-lying electronic structure exhibits a spatially anisotropic dip-like feature robust against magnetic fields. Superconductivity in FeSe/BLG/SiC, however, emerges for thicker films with Tc = 6 K.
Keywords: FeSe; LT-STM/STS; iron-based superconductor; molecular beam epitaxy; superconductivity