Magnetic susceptibility of Hgl-xFexSe

Z. So~ki6 a'*, B. Babi6 Stojib a, M. Stojib a, D. Milivojevib a, A. Szytula b, Z. Tomkowicz b Institute of Nuclear Sciences Vin~'a, P.O. Box 522, 11001 Belgrade, Yugoslavia b Institute of Physics, Jagellonian University. 30059 Krakow, Poland Received 4 May 1997 Abstract The low field AC magnetic susceptibility of Hgl_xFe~Se (x = 0.045, 0.070 and 0.095) has been measured in the temperature range 12 150 K. Our experimental data as well as those reported earlier are compared with the extended nearest-neighbour pair approximation calculations taking into account the long-range antiferromagnetic exchange interaction between Fe 2 + ions in the form