RANDOM MAGNETISM OF O-2 CONFINED IN A SLIT-SHAPED GRAPHITIC NANOSPACE AT LOW-TEMPERATURE

The temperature dependence of the magnetic susceptibility (chi) of O-2 molecules adsorbed in slit-shaped carbon micropores of 1 nm in width was measured as a function of the coverage r at 1.7-100 K. The adsorbed O-2 molecules below rho = 0.2 showed the paramagnetism without any obvious magnetic transition, which was quite close to the magnetism of bulk gaseous oxygen. An antiferromagnetic behavior appeared with an increase in rho. This behavior was not caused by the formation of 2D lattices or bulk solid structures, but by the random magnetism. These results indicated that O-2 molecules adsorbed in the micropore do not form any 2D magnetic lattice, but clusters before the formation of the bulk solid structure.