| 1. |
- Hellsvik, Johan, et al.
(författare)
-
Ultrafast cooling and heating scenarios for the laser-induced phase transition in CuO
- 2016
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 94:14
-
Tidskriftsartikel (refereegranskat)abstract
- The multiferroic compound CuO exhibits low-temperature magnetic properties similar to antiferromagnetic iron oxides, while the electronic properties have much more in common with the high-Tc cuprate superconductors. This suggests novel possibilities for the ultrafast optical excitation of magnetism. On the basis of atomistic spin dynamics simulations, we study the effect of phonon-assisted multimagnon absorption and photodoping on the spin dynamics in the vicinity of the first-order phase transition from collinear to spin-spiral magnetic order. Similar as in recent experiments, we find that for both excitations the phase transition can proceed on the picosecond timescale. Interestingly, however, these excitation mechanisms display very distinct dynamics. Following photodoping, the spin system first cools down on subpicosecond time scales, which we explain as an ultrafast magnetocaloric effect. Opposed to this, following phonon-assisted multimagnon excitation, the spin systems rapidly heats up and subsequently evolves to the noncollinear phase even under the influence of isotropic exchange interactions alone.
|
|
| 2. |
- Mentink, J. H., et al.
(författare)
-
Ultrafast Spin Dynamics in Multisublattice Magnets
- 2012
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:5, s. 057202-
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a general theoretical framework for ultrafast laser-induced spin dynamics in multisublattice magnets. We distinguish relaxation of relativistic and exchange origin and show that when the former dominates, nonequivalent sublattices have distinct dynamics despite their strong exchange coupling. Even more interesting, in the exchange dominated regime sublattices can show highly counterintuitive transitions between parallel and antiparallel alignment. This allows us to explain recent experiments with antiferromagnetically coupled sublattices, and predict that such transitions are possible with ferromagnetic coupling as well. In addition, we predict that exchange relaxation enhances the demagnetization speed of both sublattices only when they are antiferromagnetically coupled.
|
|
