TY  - JOUR
A1  - Liu, Chun-Yu
A1  - Ruotsalainen, Kari
A1  - Bauer, Karl
A1  - Decker, Régis
A1  - Pietzsch, Annette
A1  - Föhlisch, Alexander
T1  - Excited-state exchange interaction in NiO determined by high-resolution resonant inelastic x-ray scattering at the Ni M2,3 edges
T2  - Physical review : B, Condensed matter and materials physics
N2  - The electronic and magnetic excitations of bulk NiO have been determined using the 3A2g to 3T2g crystal-field transition at the Ni M2,3 edges with resonant inelastic x-ray scattering at 66.3- and 67.9-eV photon energies and 33-meV spectral resolution. Unambiguous assignment of the high-energy side of this state to a spin-flip satellite is achieved. We extract an effective exchange field of 89±4 meV  in the 3T2g excited final state from empirical two-peak spin-flip model. The experimental data is found consistent with crystal-field model calculations using exchange fields of 60–100 meV. Full agreement with crystal-field multiplet calculations is achieved for the incident photon energy dependence of line shapes. The lower exchange parameter in the excited state as compared to the ground-state value of 120 meV is discussed in terms of the modification of the orbital occupancy (electronic effects) 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 of antiferromagnetism 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 femtosecond scattering duration is derived.
Y1  - 2022
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/62015
SN  - 2469-9950
SN  - 2469-9969
VL  - 106
IS  - 3
PB  - American Physical Society
CY  - Ridge, NY
ER  -