Condensed-Matter Physics & Materials Science Seminar

Resonant X-ray Scattering (RXS), Scanning Tunneling Spectroscopy (STS) and Angle-Resolved Photo-Emission Spectroscopy (ARPES) measurements have been at the forefront of several advances in the studies of quantum materials. Our group specializes in these techniques, looking to leverage their combination to the study of quantum materials. I will discuss two projects where we have used these state-of-the-art techniques to study high-temperature superconductors and topological materials. Charge order has now been ubiquitously observed in cuprate high-temperature superconductors. However, it remains unclear if the charge order is purely static or whether it also features dynamic correlations. I will discuss a polarization-resolved soft x-ray inelastic RXS experiment with unprecedented resolution that demonstrates the existence of a coupling between dynamic magnetic and charge-order correlations in the electron-doped cuprate Nd2−xCexCuO4 [1-3]. I will also discuss a combined ARPES-STS study of the topological material Hf2Te2P. Similar to the reports by H. Ji, et al. on Zr2Te2P [4], band structure calculations and ARPES by Hosen et al. [5] also suggest multiple topological surface states in Hf2Te2P. However, some topological surface states still lacked direct spectroscopic evidence due the inability of ARPES experiments to probe the unoccupied band structure. Using the combination of STS and ARPES with surface K-doping, we probe the unoccupied band structure of Hf2Te2P and demonstrate the presence of multiple surface states with a linear Dirac-like dispersion, consistent with the predictions from previously reported band structure calculations [6]. [1] E. H. da Silva Neto, et al. Science 347, 282 (2015). [2] E. H. da Silva Neto, et al. Science Advances 2 (8), e1600782 (2016). [3] E. H. da Silva Neto, et al. Physical Review B, Rapid Communication 98, 161114(R) (2018). [4] H. Ji, et al. Physical