Unusual superexchange pathways in an NiS2 triangular lattice with negative charge-transfer energy.
We have studied the electronic structure of the Ni triangular lattice in NiGa(2)S(4) using photoemission spectroscopy and subsequent model calculations. The cluster-model analysis of the Ni 2p core-level spectrum shows that the S 3p to Ni 3d charge-transfer energy is approximately -1 eV and the ground state is dominated by the d(9)L configuration (L is a S 3p hole). Cell perturbation analysis for the NiS(2) triangular lattice indicates that the strong S 3p hole character of the ground state provides the enhanced superexchange interaction between the third-nearest-neighbor sites.
Department of Physics & Department of Complexity Science and Engineering, University of Tokyo, Chiba 277-8561, Japan.
K
K
Takubo
T
T
Mizokawa
J-Y
JY
Son
Y
Y
Nambu
S
S
Nakatsuji
Y
Y
Maeno