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

Mikhaylovskiy, R., V; Huisman, T. J.; Gavrichkov, V. A.; с соавторами. PHYSICAL REVIEW LETTERS. DOI:https://doi.org/10.1103/PhysRevLett.125.157201

The microscopic origin of ultrafast modification of the ratio between the symmetric (J) and antisymmetric (D) exchange interaction in antiferromagnetic iron oxides is revealed, using femtosecond laser excitation as a pump and terahertz emission spectroscopy as a probe. By tuning the photon energy of the laser pump pulse we show that the effect of light on the D/J ratio in two archetypical iron oxides FeBO3 and ErFeO3 is maximized when the photon energy is in resonance with a spin and parity forbidden dd transition between the crystal-field split states of Fe3+ ions. The experimental findings are supported by a multielectron model, which accounts for the resonant absorption of photons by Fe3+ ions. Our results reveal the importance of the parity and spin-change forbidden, and therefore often underestimated, dd transitions in ultrafast optical control of magnetism.