Magnetic phase transitions in compounds

Abstract

Spin-reorientation transitions in compounds have been studied by measuring the temperature dependence of the a.c. susceptibility and the magnetization. The angular dependence of the magnetization on the applied field was measured on magnetically aligned samples in a SQUID magnetometer. In , the easy magnetization direction at room temperature was determined by x-ray diffraction to be the c-axis; at low temperatures, the SQUID measurements show a cone to be stable. At temperatures between 170 and 250 K, the SQUID measurements display more complex behaviour, which is attributed to the occurrence of a first-order magnetization process in this compound. The easy magnetization direction of compounds with changes from easy c-axis at high temperatures via a basal plane to easy cone at low temperatures. The magnetic phase diagram of the system is given. For , the critical field of the FOMP transition below 230 K, which corresponds to the critical temperature of the first-order transition, and the anisotropy fields at temperatures ranging from 240 to 300 K have been further investigated by means of the SPD technique.

Magnetostrictive strain effects in NdFe11Ti

“…Our MS measurement results are in good agreement with the literature [10], where Liu et al reported a spin reorientation from cone structure (θ = 53°, the angle between the average magnetic moment and c-axis) at T SR1 = 150 K to c-axis at T SR2 ≈ 200 K. Also, Pareti et al [5] reported a spin reorientation phase transition in this compound at 163 K, which is very near to our results (T SR1 = 160 K).…”

“…As shown in Fig. 4, there are very clear anomalies in these results which are associated with the spin reorientation transition in the NdFe 11 Ti compound [10]. Anomalous behavior of the susceptibility extends over the temperature interval 160-220 K, namely from the onset of the spin reorientation (T SR1 = 160 K) to the completing temperature of this phenomenon (T SR2 = 220 K).…”