Low temperature anomalies in the mixed dysprosium-yttrium iron garnets with a connection to the magnetodielectric property

摘要: The anomalous magnetic properties of the bulk mixed dysprosium-yttrium iron garnets (DyxY3-xIGs) due to the well-known spontaneous spin reorientation (SR) between the< 111> phase at high temperature and the angular phases at low temperatures was revisited recently [1, and references therein]. The SR transition was found to occur at TSR (H= 0, x)= 14.62±0.5 K, a temperature independent of the content x. Belov [2] predicted the existence of a low-temperature point TB for ferrimagnets such DyIG at about of 42 K as it was indeed observed in the experiments [3, 4]. Therefore, it is of a great interest to determine if the DyxY3-xIG compounds exhibit such TB-point and to investigate possible correlations between magnetodielectric effects revealed before in DyIG [5–7] and the anomalies observed at TSR and TB. We report in this work, isothermal magnetizations M (H) obtained in the 2-300 K range in high DC magnetic fields H up to 16 T applied on single crystals with x= 1.5, 2.0, 2.5, 3, which have a compensation point Tcomp (x) at about of 116.5, 133.5, 192.0, and 218.5 K, respectively. The measurements were performed on the samples which were allowed to rotate freely and oriented along the principal directions. Anomalies are observed around 42 K in the temperature variations of the paraprocess magnetic susceptibility, the absolute value of the parameter? b?(T) of the bH2 term in the development of M (H) to the second order, the derivatives with respect to T of both the spontaneous magnetization, and the absolute value of the modulus of the magnetic moment vector m of the Dy3+ ion. It is observed that TB seems practically independent of …