S. N. Bhatia

Magnetic properties of trimethylammonium trichlorocobaltate dihydrate and its deuterium analog

Measurements are reported of the specific heat and single-crystal principal susceptibilities in the helium region of ((CH/sub 3/)/sub 3/ND)CoCl/sub 3/ . 2D/sub 2/O and compared with those of protonic material. The effect of deuteration on the magnetic ordering temperature as well as on the exchange parameters is negligible. Because of the weak ferromagnetism of this material, sample size and shape affect the accuracy of magnetic measurements, causing a larger effect on the results than does the replacement of hydrogen by deuterium.

Paramagnetic and antiferromagnetic properties of tris(ethylenediamine)nickel(II) nitrate

Abstract Crystals of uniaxial [Ni(NH 2 CH 2 CH 2 NH 2 ) 3 ](NO 3 ) 2 have been examined between 0.3 and 30 K by means of specific-heat and susceptibility measurements. Long-range antiferromagnetic order sets in at 1.25 K, with the preferred axis along the crystal c axis. The magnetic phase diagram has been determined from the field-dependent susceptibilities, the bicritical point occurring at 0.62 ± 0.01 K and 13.9 ± 0.1 kOe. Relaxation effects were observed in the frequency-dependent susceptibilities. The following quantities have also been determined: g = 2.21 ± 0.05, g = 2.24 ± 0.05, D / k = -1.00 ± 0.05 K , J / k = -0.19 K , H SF (0) = 12.8 ± 0.2 kOe , H c (0) = 24.0 ± 0.2 kOe , H cl (0) = 37.5 ± 0.2 kOe , H E = 15.4 ± 0.1 kOe , H A = 6.8 ± 0.1 kOe , and b = 9.45 JK / mol . An exchange path for this weakly anisotropic Heisenberg antiferromagnet is proposed.