THE MAGNETIC STATE OF DIAMAGNETICALLY DILUTED ANTIFERROMAGNETIC COBALT MONOXIDE

Magnetic neutron diffraction measurements have been performed on (Co1- xMgx)O solid solutions with x = 0.1, 0.2, 0.3, 0.43, 0.53, 0.63 and 0. 7 at T = 4.2-300 K. It is shown that the concentration dependence of t he average magnetic moment per atom does not obey the condition of sim ple dilution. The diamagnetic atom results in a local canting of the m oments and an additional reduction of the average magnetic moment. One can consider this atom as a source of random magnetic field due to th e appearance of a new superexchange interaction between magnetic atoms through the diamagnetic impurity. The sign of this interaction is opp osite to the sign of the direct exchange interaction in the magnetic s ublattice. Copyright (C) 1996 Elsevier Science Ltd.