Description:

The synthesis of epitaxial quantum materials provides opportunities to explore interesting phenomena that emerge from the interplay between factors such as dimensionality, broken symmetry, spin-orbit interaction, and topology [1]. This talk will provide an overview of a synthesis-based user facility (the 2D Crystal Consortium) aimed at developing state of the art epitaxial quantum materials, followed by a discussion of two classes of Fe-chalcogenide-based heterostructures synthesized in the 2DCC that yield emergent superconductivity. We first focus on new insights into enhanced superconductivity in the structurally and stoichiometrically simple material system FeSe when interfaced with SrTiO3 (STO) substrates [2]. Such FeSe/STO thin films have attracted significant interest in recent years because the superconducting critical temperature is greatly enhanced compared to that of bulk single crystals of FeSe. We use magnetoresistance measurements in superconducting ultrathin FeSe films at high magnetic field (μ0H < 65 T) and low temperature (T > 500 mK) to gain fresh insights into the pair-breaking mechanism through the behavior of the upper critical field (Hc2). The second example centers on the emergent superconductivity discovered in heterostructures that interface a metallic antiferromagnet (FeTe) with a ferromagnetic topological insulator (Cr-doped (Bi,Sb)2Te3) [3]. These heterostructures show the surprising coexistence of superconductivity, magnetic order, and topological surface states, providing a materials platform of potential interest for quantum technologies. 

This work is supported by the Penn State Two-Dimensional Crystal Consortium-Materials Innovation Platform (2DCC-MIP) under NSF Grant No. DMR-2039351 and the Penn State Center for Nanoscale Science/MRSEC under NSF Grant No. DMR-2011839.

1.     Nitin Samarth, "Quantum materials discovery from a synthesis perspective," Nature        Materials 16, 1068-1076 (2017). 
2.     M. Stanley et al., “Temperature dependence and limiting mechanisms of the upper critical field of FeSe thin films,“Phys. Rev. B 109, 094514 (2024).
3.     H. Yi et al., “Interface-induced superconductivity in magnetic topological insulators,” Science 383, 634-639 (2024).

Nitin Samarth, Professor, Penn State University

Host: Venkat Chandrasekhar