Resonant Pumping of d−d Crystal Field Electronic Transitions as a Mechanism of Ultrafast Optical Control of the Exchange Interactions in Iron Oxides

Controlling the anisotropy of a van der Waals antiferromagnet with light

“…Our experimental results can thus be interpreted alternatively as being indicative of the resonant enhancement of the scattering process upon approaching the transition to the higher-level 3 T 2g orbital state, underlining the strong impact of the low-symmetry trigonal 3 T 2g states on the magnetic anisotropy of NiPS 3 . Several works reported that magnetic ISRS processes in iron-based compounds can be significantly enhanced in the vicinity of the d-d transitions [see, for example, (14,15)]. Our experiment shows that almost no magnon excitation is observed for the photon energies below the 3 A 2g → 3 T 2g resonance, contrary to what is expected for the ISRS process.…”

“…In these systems, magnetic anisotropy originates from the spin orbit-driven mixing of the ground state with higher-energy orbital states characterized by an unquenched momentum, a rather small effect. Optical pumping of the electronic transitions toward the higher-level orbital states (orbital resonances) provides the most direct access to the admixing and subsequent control of the magnetic anisotropy as manifested by the excitation of spin precession in 3D magnets (12)(13)(14)(15) even to the extent of the subcycle coherent switching of the spin orientation (16)(17)(18). Resonant pumping of orbital transitions in 2D magnets, characterized by the subtle interplay between anisotropy and magnetic order, offers unique insights into dynamics of their highly nontrivial elementary excitations, such as, for example, topological magnons (19,20).…”

Ultrafast photoinduced dynamics in Prussian blue analogues

“…[44][45][46] This interest was initiated by the surprising discovery that fs laser pulses could affect long-range magnetic order on the 100 fs timescale by Beaurepaire et al 47 Long-range magnetic order is key for data storage applications, because the non-volatility means that the information is stored after the laser pulse, in contrast to the work on semiconductors mentioned above. It is now possible to completely reverse the magnetisation direction using a single fs laser pulse in thin films of some metallic, 44 and, more recently, dielectric [48][49][50] materials. Interestingly, the magnetisation is observed to be quenched on timescales faster than the spin-phonon relaxation time, which raised the question about the conservation of angular momentum if the phonons are not engaged in the first 100 fs (spin is, of course, a form of angular momentum).…”

Numerically Denoising Thermally Tunable and Thickness‐Dependent Terahertz Signals in ErFeO3 Based on Bézier Curves and B‐Splines

“…In ErFeO 3 , quasiantiferromagnetic and quasiferromagnetic modes were reported by Mikhaylovskiy et al., [ 18 ] and later they correlated these two resonances with d–d transitions in 2020. [ 19 ] Magnetic field induced discontinuous spin reorientation in ErFeO 3 endows temperature engineering THz responses as we introduce a numerical method to denoise THz responses. [ 20 ] Thus, polycrystalline ErFeO 3 ceramic is chosen and prepared.…”