Caitlin Duffy : Spin, scattering, and superconductivity in electron-doped cuprates

In the 40 years since the discovery of high-Tc superconductivity, the cuprate problem has blossomed into a healthy series of puzzles that have inspired several generations of physicists. Despite the abundance of experimental and theoretical advances that have been made, the mystery behind high-Tc superconductivity remains unsolved.

In conventional phonon-mediated superconductors, the superconducting transition temperature and the quasiparticle scattering rate are related through the electron-phonon coupling strength. In the cuprates no such coupling strength has yet been found, despite the provocative correlation between the T-linear resistivity and Tc.  Although electron- and hole-doped cuprates share similar attributes, the former hosts a weaker superconducting phase that partly coincides with short-range antiferromagnetic fluctuations. Additionally, the transport properties differ significantly raising the question of whether the same superconducting pairing mechanism is at play in both electron- and hole-doped cuprates.

In this seminar, I will discuss magnetoresistance measurements on thin films of the electron-doped cuprate La2-x CexCuO4 (LCCO). I will explain how a form of the quasiparticle scattering rate is deduced from experimental data, and then use this within a Boltzmann framework to elucidate an effective coupling parameter for superconductivity. Analysis of the Hall effect then attributes this coupling parameter to scattering off antiferromagnetic spin fluctuations, identifying these as the pairing mechanism for superconductivity in electron-doped cuprates. I will highlight several pertinent problems that remain and directions for future studies.

C. M. Duffy et al., arXiv:2502.13612

R. Cooper et al., Science 323, 603-607 (2009)

K. Jin et al., Nature 476, 73–75 (2011)

T. Sarkar et al., Phys. Rev. B 103, 224501 (2021)