Magnetic transitions in single-crystal thulium

The magnetic transitions in a thulium single crystal have been investigated with magnetization, AC susceptibility and high-resolution calorimetric measurements. The results give clear evidence of the antiferromagnetic transition at 58 K, the squaring up of the magnetic moments between 42 and 35 K, and the ferrimagnetic transition at 33 K. The transition at 33 K is of first order with a latent heat of 0.8+or-0.2 J mol-1. The magnetic moment in the ferrimagnetic state measured with a SQUID magnetometer is (1.025+or-0.001) consistent with the expected 7.0 mu B per atom and a 3, -4 antiphase domain structure. At 30 kOe afield-induced transition to ferromagnetic order takes place. In this state the moment is found to be (7.060+or-0.001) mu B. The excess moment of 6*10-2 mu B for the ferromagnetic saturation magnetization in thulium is tentatively attributed to polarization of the conduction electrons.