Prof. Milan Allan
LMU Munich / Leiden University

What causes superconductivity to disappear at the critical temperature Tc in quantum materials? In my talk, I will discuss two examples. First, I will present the case of underdoped cuprate superconductors, where a pseudogap exists far above Tc. Whether the pseudogap energy is associated with pairing has been a key question debated for decades. Using novel shot-noise experiments, we found that the pseudogap energy is equal to the pairing energy, meaning that pairing persists to very high energies - therefore, superconductivity is limited by coherence [1]. Next, 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 [2].

References:
[1] Niu & Ortego, et al. arXiv:2409.15928
[2] Tromp & Benschop, et al. Nature Materials (2023)