Speaker
Description
Ultrafast order melting in magnetic insulators is governed by two processes: intrinsic intra-spin relaxation and spin-lattice energy transfer. Antiferromagnets, which lack net magnetization, can in principle evade angular-momentum constraints and display markedly faster order-parameter dynamics than ferromagnets, but experimental rates vary widely across materials. Here we combine first-principles magnetostriction calculations, phonon and magnon spectral analysis, atomistic spin-dynamics simulations and time-resolved second-harmonic generation to disentangle these pathways and explain material-dependent disparities. Focusing on two structurally similar antiferromagnets, Cr2O3 and FeBO3, we show that the strength of spin-phonon coupling - revealed by magnetostrictive response and phonon-magnon spectral overlap - dictates the dramatic difference in order-melting rates. We also achieved accelerated dynamics in Cr2O3 and show sub-2-ps order melting in both experiment and simulation. Our results establish spin-phonon coupling as the decisive control parameter for ultrafast antiferromagnetic dynamics and provide a practical framework to design faster switching in antiferromagnetic spintronic devices.