Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:

What causes superconductivity to disappear at the critical temperature Tc in quantum materials? In my talk, I will present two materials: First, I will show how in the disordered superconductor titanium nitride, electron pairs exist far above Tc. For this study, we developed new instrumentation that can unambiguously and quantitatively detect electron pairs: the electron pair microscope [1,2]. We discovered a state above Tc that, much like an ordinary metal, has no (pseudo)gap, but appears to carry charge entirely via paired electrons. [3]. Second, I will discuss overdoped high-temperature superconductors, where we found that superconductivity breaks down because of the formation of nanometer-sized puddles in a metallic matrix. Again, superconductivity is not limited by the pairing interaction [4].

References

[1] KM Bastiaans et al., RSI 89, 093709 (2018)

[2] KM Bastiaans, D. Cho et al., Nature Physics 14, 1183 (2018)

[3] KM Bastiaans, et al. Science 374, 608 (2021)

[4] Tromp & Benschop, et al. Nature Materials (2023)

More about the Speaker:
Milan Allan is proffessor at the University of Munich (LMU), currently moving there from Leiden University. Milan and his group study quantum matter on the atomic scale using novel scanning probe techniques, including electron pair microscopy. Milan received his "Diplom" from ETH Zurich (cum laude), and his PhD from the University of St Andrews. After postdocs at Cornell (as a PhD+ fellow) and ETH Zurich (as an ETH fellow), he joined Leiden University in 2015 and is currently moving to LMU. Milan won the Bryan R. Coles prize, the NWO Vidi, and the ERC Starting and Consolidator Grants.