arXiv subjects

M. Seaberg

Publications and source records attributed to M. Seaberg.

4 recordsLinked to original sources

arXiv2025

Memory in strain-tuned insulator-metal-insulator sequence of transitions after photoexcitation in the Mott material V2O3

Memory effects during metal-insulator transitions in quantum materials reveal complex physics and potential for novel electronics mimicking biological neural systems. Nonetheless, understanding of memory and nonlinearity in sequential non-equilibrium transitions remains elusive as the full chain of transitions can involve features lasting anywhere from femtoseconds to microseconds. Here, we extend time-resolved x-ray Bragg diffraction to the dynamic range of timescales spanning 9 orders of magnitude to fully trace the pathways of photoexcited insulator-metal transition and the following relaxation through non-equilibrium metal-insulator transitions in epitaxial films of V2O3, a promising Mott material. We find 5 orders of magnitude variation in metal-insulator transition time, from nanoseconds to hundreds of microseconds, depending on pre-excitation phase state. We provide a theoretical explanation and simulations based on strain feedback to domain nucleation. The lingering transition is stretched in time by memory of spatial and energy heterogeneity and, contrary to known memory effects in vanadium oxides commonly described by power laws, follows an extremely (factor below 0.2) stretched exponential. The induced dramatic slowdown in the light-driven highly correlated system signifies unusually high heterogeneity of transition barriers similar to biological systems, and demonstrates importance of non-local correlations of structure in evolution of transitional phases in quantum materials.

cond-mat.mtrl-sci↗

arXiv2021

A Snapshot Review -- Fluctuations in Quantum Materials: From Skyrmions to Superconductivity

By measuring a linear response function directly, such as the dynamic susceptibility, one can understand fundamental material properties. However, a fresh perspective can be offered by studying fluctuations. This can be related back to the dynamic susceptibility through the fluctuation-dissipation theorem, which relates the fluctuations in a system to its response, an alternate route to access the physics of a material. Here, we describe a new x-ray tool for material characterization that will offer an opportunity to uncover new physics in quantum materials using this theorem. We provide details of the method and discuss the requisite analysis techniques in order to capitalize on the potential to explore an uncharted region of phase space. This is followed by recent results on a topological chiral magnet, together with a discussion of current work in progress. We provide a perspective on future measurements planned for work in unconventional superconductivity.

cond-mat.str-el↗

arXiv2017

Optically induced lattice deformations, electronic structure changes, and enhanced superconductivity in YBa2Cu3O6.48

Resonant optical excitation of apical oxygen vibrational modes in the normal state of underdoped YBa2Cu3O6+x induces a transient state with optical properties similar to those of the equilibrium superconducting state. Amongst these, a divergent imaginary conductivity and a plasma edge are transiently observed in the photo-stimulated state. Femtosecond hard x-ray diffraction experiments have been used in the past to identify the transient crystal structure in this non-equilibrium state. Here, we start from these crystallographic features and theoretically predict the corresponding electronic rearrangements that accompany these structural deformations. Using density functional theory, we predict enhanced hole-doping of the CuO2 planes. The empty chain Cu dy2-z2 orbital is calculated to strongly reduce in energy, which would increase c-axis transport and potentially enhance the interlayer Josephson coupling as observed in the THz-frequency response. From these calculations, we predict changes in the soft x-ray absorption spectra at the Cu L-edge. Femtosecond x-ray pulses from a free electron laser are used to probe these changes in absorption at two photon energies along this spectrum, and provide data consistent with these predictions.

cond-mat.supr-con↗

arXiv2010

Bright, Coherent, Ultrafast Soft X-Ray Harmonics Spanning the Water Window from a Tabletop Light Source

We demonstrate fully phase matched high-order harmonic generation with emission spanning the water window spectral region important for bio- and nano-imaging and a breadth of materials and molecular dynamics studies. We also generate the broadest bright coherent bandwidth (~300eV) to date obtained from any light source, small or large. The harmonic photon flux at 0.5 keV is 10^3 higher than demonstrated previously, making it possible for the first time to demonstrate spatial coherence in the water window. The continuum emission is consistent with a single attosecond burst, that extends bright attosecond pulses into the soft x-ray region.

physics.optics↗