MAGNETIZATION AND MAGNETIC-SUSCEPTIBILITY OF CO BASED HGSE WITH LOW CO CONCENTRATION - SYMMETRY INDUCED ZERO GAP SITUATION

In symmetry induced zero gap Hg1-xCoxSe for x lower than 1%, magnetization and susceptibility are measured. The magnetization at 4.2 K is very well fitted with isolated Co2+, whereas, at 1.5 K for the lowest Co concentration, the Co3+ contribution must be taken into account as a corrective part. The magnetic susceptibility shows two slopes. The first one under 80 K corresponds to antiferromagnetic interactions in agreement with the T0 obtained from magnetization. The second one above 80 K shows ferromagnetic interactions which cannot be explained in terms of RKKY model and are probably due to the presence of CoSe clusters in our samples.