Ultrafast Enhancement of Ferromagnetic Spin Exchange Induced by Ligand-to-Metal Charge Transfer

We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground s...

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Bibliographic Details
Published in:Physical review letters 2020-11, Vol.125 (19), p.1-197203, Article 197203
Main Authors: Ron, A., Chaudhary, S., Zhang, G., Ning, H., Zoghlin, E., Wilson, S. D., Averitt, R. D., Refael, G., Hsieh, D.
Format: Article
Language:English
Subjects:
Charge transfer
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Ferromagnetism
Ligands
MATERIALS SCIENCE
Physics
Spin exchange
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Summary:We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground state. We demonstrate this effect in the layered ferromagnetic insulator CrSiTe 3 by exciting Te-to-Cr charge-transfer transitions using ultrashort laser pulses and detecting coherent phonon oscillations that are impulsively generated by superexchange enhancement via magneto-elastic coupling. This mechanism kicks in below the temperature scale where short-range in-plane spin correlations begin to develop and disappears when the excitation energy is tuned away from the charge-transfer resonance, consistent with our predictions.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.125.197203