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Condensed Matter > Strongly Correlated Electrons
Title: Dynamic magnetic phase transition induced by parametric magnon pumping
(Submitted on 14 Feb 2024 (v1), last revised 17 Apr 2024 (this version, v2))
Abstract: Uncovering pathways to optically drive magnetic order-disorder transitions on ultrashort timescales can lead to the realization of novel out-of-equilibrium quantum phenomena. A long-sought pathway is to directly excite a highly non-thermal energy-momentum distribution of magnons, bypassing both charge and lattice degrees of freedom. However, this remains elusive owing to the weak coupling and large momentum mismatch between photons and magnons. Here we demonstrate strong parametric excitation of magnons across the entire Brillouin zone of the antiferromagnetic insulator Sr$_2$Cu$_3$O$_4$Cl$_2$ by periodically modulating the superexchange interaction with the electric field of light. The excitation efficiency is greatly enhanced by tuning to the van Hove singularity in the magnon spectrum, sufficient to transiently collapse the antiferromagnetic state using a pulsed laser field of 10$^9$ V/m. The order parameter recovery timescale increases by over 1000 times as a function of excitation density, reflecting a crossover from high- to low-energy magnon dominated decay dynamics. This electric-field induced parametric magnon pumping mechanism is applicable to a broad range of magnetic insulators and opens up the possibility of dynamically engineering magnon distributions by design.
Submission history
From: Junyi Shan [view email][v1] Wed, 14 Feb 2024 19:00:29 GMT (3531kb,D)
[v2] Wed, 17 Apr 2024 16:34:04 GMT (0kb,I)
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