The Myron Strongin Seminar Series

In transition metal systems where the orbital degeneracies are anticipated in their high symmetry structural phases, crystallographic symmetry lowering at the temperature driven structural phase transitions is often assumed to imply simultaneous orbital degeneracy lifting (ODL) by engaging some cooperative mechanism. Consequently, seemingly mundane high temperature regimes possessing high crystallographic symmetry remain much less explored. In contrast to this concept, recent utilization of probes sensitive to local symmetry qualified the ODL as a local electronic effect existing at temperature well above the global symmetry breaking transitions. This presentation will showcase observations of fluctuating local-structural distortions at high temperature in several transition metal-based quantum materials exhibiting orbital-selective ground states. Such local orbital states come in different flavors (e.g., engaging single or multiple transition metal d orbitals) and are likely to exist both in the proximity to itinerant-to-localized crossover and deep in the regime of suppressed charge fluctuations. These observations suggest that such precursor states are possibly widespread amongst diverse classes of partially filled nominally degenerate d-electron systems, with potentially broad implications for our understanding of their properties.

[1] Nature Comms. 10, 3638 (2019)
[2] Phys. Rev. B 100, 020501(R) (2019)
[3] Phys. Rev. B 102, 235128 (2020)
[4] arXiv:2009.14288 (2021)