SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 20: Spintronics (other effects)
MA 20.3: Vortrag
Dienstag, 28. März 2023, 15:30–15:45, HSZ 401
Excited-state exchange interaction in NiO determined by high-resolution resonant inelastic x-ray scattering at the Ni M2,3 edges — •Chun-Yu Liu1,2, Kari Ruotsalainen1, Karl Bauer1, Régis Decker1, Annette Pietzsch1, and Alexander Föhlisch1,2 — 1Institute for Methods and Instrumentation for Synchrotron Radiation Research (PS-ISRR), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Albert-Einstein-Strasse 15, 12489 Berlin, Germany — 2Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
The electronic and spin excitations of bulk NiO have been determined using the 3A2g to 3T2g crystal-field transition at the Ni M2,3 edges with high resolution resonant inelastic x-ray scattering. We extract an effective exchange field of 89±4 meV in the 3T2g excited final state from empirical two-peak spin-flip model, which is further confirmed with crystal-field model calculations using exchange fields of 60-100 meV. The lower exchange parameter in the excited state is discussed in terms of the modification of the orbital occupancy and of the structural dynamics: (A) With pure electronic effects, the lower exchange energy is attributed to the reduction in effective hopping integral. (B) With no electronic effects, we use the S = 1 Heisenberg model to derive a second-nearest-neighbor exchange constant J2 = 14.8±0.6 meV. Based on the linear correlation between J2 and the lattice parameter from pressure-dependent experiments, an upper limit of 2% local Ni-O bond elongation during the fs scattering duration is derived.