Spin model of O-based magnet in a nanoporous metal complex

Soda, Minoru*; Homma, Yuki*; Takamizawa, Satoshi*; Kawamura, Seiko   ; Nakajima, Kenji  ; Masuda, Takatsugu*

Inelastic neutron scattering experiments are performed on the nanoporous metal complex Cu--1,4-cyclohexanedicarboxylic acid (Cu-CHD) adsorbing O molecules to identify the spin model of the O-based magnet realized in the host complex. It is found that the magnetic excitations of Cu-CHDs adsorbing low- and high-concentration O molecules are explained by different spin models, the former by spin dimers and the latter by spin trimers. By using the obtained parameters and by assuming that the levels of the group of the highest energy states are reduced because of the nonnegligible spin dependence of the molecular potential of oxygen, the magnetization curves are explained quantitatively.