Talk 1:
Fermi Surface Expansion above Critical Temperature in Ferromagnets: A cDMFT and DΓA Study
Ryotaro Arita, Research Center for Advanced Science and Technology, The University of Tokyo and RIKEN Center for Emergent Matter Science
Using a cluster and diagrammatic extension of the dynamical mean-field theory, we study the single- and two-orbital Hubbard models with strong ferromagnetic (FM) spin fluctuations. We find a significant expansion of the Fermi surface (FS) above the Curie temperature (Tc). While it is natural to see a volume expansion of the majority-spin FS in the FM long-range-ordered metal below Tc, we find a similar spectrum even above Tc in the strong-coupling regime with the large preformed local moment [1,2].
[1] Y. Nomura, S. Sakai and R. Arita, PRL 128 206401 (2022)
[2] M. Kitatani et al., in prep.
Talk 2:
Simulating Correlation Effects in Quasi-2D Materials
Jan M. Tomczak, Department of Physics, King’s College London and Institute of Solid-State Physics, TU Wien
About 20 years ago, the synthesis of two-dimensional crystals and heterostructure meta-materials started a revolution in condensed-matter physics: Graphene, transition-metal dichalcogenides, and atomically precise interfaces and ultrathin films allowed the study and discovery of many new phenomena—absent in 3D bulk samples. Here, we will discuss some results, challenges, and opportunities for the simulation of (quasi-)2D materials with strong correlation effects: The rich (but fragile) phase diagram of ultrathin SrVO3 films [1] suggested for use as Mott transistor [2], the connection between strong non-local fluctuations and momentum-dependent renormalizations in those films [3], and the “Coulomb engineering” of 2D Mott materials, where a temporary (and/or spatial) variation in the dielectric environment may trigger a selective insulator-to-metal transition, suggesting application in sensors (or novel circuitry) [4].
[1] M. Pickem, J. Kaufmann, K. Held, JMT, Phys. Rev. B 2, 024307 (2021)
[2] Z. Zhong et al, Phys. Rev. Lett. 114, 246401 (2015)
[3] M. Pickem, JMT, K. Held, Phys. Rev. Research 4, 033253 (2022)
[4] E.G.C.P. van Loon et al, npj 2D Materials and Applications 7, 47 (2023)
