Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLaser-Induced Transient Magnons in Sr3Ir2O7 Throughout the Brillouin Zone
123
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Although ultrafast manipulation of magnetism holds great promise for new physical phenomena and applications, targeting specific states is held back by our limited understanding of how magnetic correlations evolve on ultrafast timescales. Using ultrafast resonant inelastic x-ray scattering we demonstrate that femtosecond laser pulses can excite transient magnons at large wavevectors in gapped antiferromagnets, and that they persist for several picoseconds which is opposite to what is observed in nearly gapless magnets. Our work suggests that materials with isotropic magnetic interactions are preferred to achieve rapid manipulation of magnetism.
rate research
Read More
Inelastic neutron scattering is used to measure spin excitations in fully deuterated single crystal samples of the strong-leg antiferromagnetic S=1/2 spin ladder compound (C$_7$H$_{10}$N)$_2$CuBr$_4$. Sharp resolution-limited magnons are observed across the entire one-dimensional Brillouin zone. The results validate the previously proposed {it symmetric} spin ladder model and provide a reliable estimate of the relevant exchange interactions.
We report here on time-resolved x-ray diffraction measurements following femtosecond laser excitation in pure bulk chromium. Comparing the evolution of incommensurate charge-density-wave (CDW) and atomic lattice reflections, we show that, few nanoseconds after laser excitation, the CDW undergoes different structural changes than the atomic lattice. We give evidence for a transient CDW shear strain that breaks the lattice point symmetry. This strain is characteristic of sliding CDWs, as observed in other incommensurate CDW systems, suggesting the laser-induced CDW sliding capability in 3D systems. This first evidence opens perspectives for unconventional laser-assisted transport of correlated charges.
We study periodically driven insulating noncollinear stacked kagome antiferromagnets with a conventional symmetry-protected three-dimensional (3D) in-plane $120^circ$ spin structure, with either positive or negative vector chirality. We show that the symmetry protection of the in-plane $120^circ$ spin structure can be broken in the presence of an off-resonant circularly or linearly polarized electric field propagating parallel to the in-plane $120^circ$ spin structure (say along the $x$ direction). Consequently, topological Floquet Weyl magnon nodes with opposite chirality are photoinduced along the $k_x$ momentum direction. They manifest as the monopoles of the photoinduced Berry curvature. We also show that the system exhibits a photoinduced magnon thermal Hall effect for circularly polarized electric field. Furthermore, we show that the photoinduced chiral spin structure is a canted 3D in-plane $120^circ$ spin structure, which was recently observed in the equilibrium noncollinear antiferromagnetic Weyl semimetals Mn$_3$Snslash Ge. Our result not only paves the way towards the experimental realization of Weyl magnons and photoinduced thermal Hall effects, but also provides a powerful mechanism for manipulating the intrinsic properties of 3D topological antiferromagnets.
We propose a scheme to determine the energy-band dispersion of quasicrystals which does not require any periodic approximation and which directly provides the correct structure of the extended Brillouin zones. In the gap labelling viewpoint, this allow to transpose the measure of the integrated density-of-states to the measure of the effective Brillouin-zone areas that are uniquely determined by the position of the Bragg peaks. Moreover we show that the Bragg vectors can be determined by the stability analysis of the law of recurrence used to generate the quasicrystal. Our analysis of the gap labelling in the quasi-momentum space opens the way to an experimental proof of the gap labelling itself within the framework of an optics experiment, polaritons, or with ultracold atoms.
In this work, we present evidence for the existence of a magnonic current on the sub-picosecond time-scale in a ferrimagnetic bilayer and its effect on ultrafast spin dynamics. The ferrimagnet, GdFeCo, is a material known to undergo ultrafast switching within 1-2ps after excitation with femtosecond laser pulses. Here, we show that the strong thermal gradients induced by applying femtosecond laser pulses and the presence of chemical inhomogeneities lead to local imbalances in the effective temperatures of the spins that produces a rapid transfer of spin angular momentum, which we interpret as an ultrafast spin Seebeck effect. We have quantified the typical magnon propagation in such a system. The results show ballistic magnon propagation with 30nm/ps velocities. The characteristic time scale of such magnon propagation indicates that this magnon transport can play an important role in switching, a crucial piece of understanding towards realising next generation data processing devices that operate at much higher frequencies.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
