Dr. Mark Dean - Brookhaven National Laboratory


Guest: Dr. Mark P.M. Dean
Physicist, Brookhaven National Laboratory

Title: Quantum materials under a resonant x-ray spotlight

Many of the most remarkable properties of quantum materials come from the interplay of multiple charge, orbital and spin degrees of freedom. Probing all of these with a single technique is consequently highly desirable. In this talk, I will describe how resonant inelastic x-ray scattering (RIXS) opens up important new possibilities for measuring all these degrees of freedom. This will be illustrated by our studies of low valence nickelates, which are a recently discovered family of strongly correlated unconventional superconductors. We show how RIXS can unveil the strength of the magnetic interactions [1], the electronic character of the charge carriers [2], and the states involved in charge order [3]. If time allows, I will also outline our recent discovery of an Antiferromagnetic excitonic insulating state [4].
1. Strong Superexchange in a d9-δ Nickelate Revealed by Resonant Inelastic X-Ray Scattering, J. Q. Lin, P. Villar Arribi, G. Fabbris, A. S. Botana, D. Meyers, H. Miao, Y. Shen, D. G. Mazzone, J. Feng, S. G. Chiuzbăian, A. Nag, A. C. Walters, M. Garcı́a-Fernández, Ke-Jin Zhou, J. Pelliciari, I. Jarrige, J. W. Freeland, Junjie Zhang, J. F. Mitchell, V. Bisogni, X. Liu, M. R. Norman, and M. P. M. Dean, Phys. Rev. Lett. 126, 087001 (2021)
2. Role of Oxygen States in the Low Valence Nickelate La4Ni3O8, Y. Shen, J. Sears, G. Fabbris, J. Li, J. Pelliciari, I. Jarrige, Xi He, I. Bozovic, M. Mitrano, Junjie Zhang, J. F. Mitchell, A. S. Botana, V. Bisogni, M. R. Norman, S. Johnston, and M. P. M. Dean, Phys. Rev. X 12, 011055 (2022)
3. Electronic character of charge order in square planar low valence nickelates, Y. Shen, J. Sears, G. Fabbris, J. Li, J. Pelliciari, M. Mitrano, W. He, Junjie Zhang, J. F. Mitchell, V. Bisogni, M. R. Norman, S. Johnston, and M. P. M. Dean, arXiv:2301.04184 to appear in Phys. Rev. X (2023)
4. Antiferromagnetic excitonic insulator state in Sr3Ir2O7, D. G. Mazzone, Y. Shen, H. Suwa, G. Fabbris, J. Yang, S.-S. Zhang, H. Miao, J. Sears, Ke Jia, Y. G. Shi, M. H. Upton, D. M. Casa, X. Liu, Jian Liu, C. D. Batista, and M. P. M. Dean, Nature Communications 13, 913 (2022)

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A.N. Bourns Science Building, 1280 Main St W, Hamilton, ON L8S 4M6, Canada

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