Reply to: Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott-Hubbard material

International audienceReplying to D. Moreno-Mencía et al. Nature Communicationshttps://doi.org/10.1038/s41467-019-11743-3 (2019)

Controlling Coulomb correlations and fine structure of quasi-one-dimensional excitons by magnetic order

Many surprising properties of quantum materials result from Coulomb correlations defining electronic quasiparticles and their interaction chains. In van der Waals layered crystals, enhanced correlations have been tailored in reduced dimensions, enabling excitons with giant binding energies and emergent phases including ferroelectric, ferromagnetic and multiferroic orders. Yet, correlation design has primarily relied on structural engineering. Here we present quantitative experiment–theory proof that excitonic correlations can be switched through magnetic order. By probing internal Rydberg-like transitions of excitons in the magnetic semiconductor CrSBr, we reveal their binding energy and a dramatic anisotropy of their quasi-one-dimensional orbitals manifesting in strong fine-structure splitting. We switch the internal structure from strongly bound, monolayer-localized states to weakly bound, interlayer-delocalized states by pushing the system from antiferromagnetic to paramagnetic phases. Our analysis connects this transition to the exciton’s spin-controlled effective quantum confinement, supported by the exciton’s dynamics. In future applications, excitons or even condensates may be interfaced with spintronics; extrinsically switchable Coulomb correlations could shape phase transitions on demand

Ultrafast photoinduced conductivity reduction by bonding orbital control in an incommensurate crystal

In this paper, we demonstrate the ultrafast reduction of conductivity in an incommensurate crystal structure within hundreds of femtoseconds. This phenomenon stands in stark contrast to most prior experimental investigations where incident light pulses led to increased conductivity. We achieve this by selectively targeting a specific atomic bond using near-infrared light pulses. Our investigation focuses on misfit layered chalcogenide (LaS)1.196VS2, known as LaVS3, a semimetal with incommensurability along one crystallographic direction. Our time-resolved electron dynamics investigation reveals that the conductivity decreases as photoexcited electrons are promoted into localized energy states within vanadium clusters due to the incommensurate structure. These findings offer insights into the potential for controlling electronic properties at femtosecond time scales, with implications for the development of ultrafast electronic devices

Dynamics of out-of-equilibrium electron and hole pockets in the type-II Weyl semimetal candidate WTe

Physical Review B. Volume 97, Issue 11, 8 March 2018, Article number 115115.© 2018 American Physical Society. We present a time- and angle-resolved photoemission study of the transition-metal dichalcogenide WTe2, a candidate type-II Weyl semimetal exhibiting extremely large magnetoresistence. Using femtosecond light pulses, we characterize the unoccupied states of the electron pockets above the Fermi level. Following the ultrafast carrier relaxation in distinct parts of the Brillouin zone, we report remarkably similar decay dynamics for electrons and holes. Our results confirm that charge compensation between electron and hole pockets - a key effect to explain the nonsaturating magnetoresistance of this material - is a distinctive feature of WTe2 even in an out-of-equilibrium regime

Data archive of "Controlling Coulomb correlations and fine structure of quasi-one-dimensional excitons by magnetic order"

Rohdaten, Dateien der endgültigen Abbildunge