INTRINSIC MAGNETIC-PROPERTIES OF RFE(10)MO(2) COMPOUNDS (R=Y, PR, ND, SM, GD, TB, DY, HO, ER, OR TM)

A systematic investigation of the intrinsic magnetic properties of RFe10Mo2 compounds (with R=Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) has been performed by means of ac susceptibility measurements, singular-point-detection techniques, and magnetization measurements. Spin reorientations were detected by measuring the temperature dependence of the ac susceptibility and the magnetization in NdFe10Mo2 (Tsr=147 K), DyFe10Mo2 (Tsr=137 K), ErFe10Mo2 (Tsr=180 K), and TmFe10Mo2 (Tsr=166 K). In order to trace field-induced magnetic phase transitions, magnetization curves were measured at 4.2 K on magnetically-aligned RFe10Mo2 samples in magnetic fields up to 35 T in the Amsterdam high field installation. First-order magnetization processes (FOMP)-like transitions were detected at 4.2 K in PrFe10Mo2 (Bcr=5.97 T) and HoFe10Mo2 (Bcr=1.73 T) in an external field applied perpendicular to the alignment direction and in ErFe10Mo2 (Bcr=2.47 T) in an external field applied parallel to the alignment direction. An anomalous increase of magnetization of SmFe10Mo2 at low temperatures in an external field applied perpendicular to the alignment direction is suggested to be due to a fast continuous rotation of magnetic moment under the action of external field, rather than due to a FOMP-type transition. The magnetic-coupling strength between the rare-earth and the transition-metal moments have been determined for the RFe10Mo2 compounds with R=Dy, Ho, Er, or Tm from the magnetization behavior in fields up to 35 T of fine single-crystalline powder particles, loaded loosely into the sample holder and therefore free to rotate in the applied magnetic field. The temperature dependence of the anisotropy field BA of the RFe10Mo2 compounds has been determined by means of the singular-point-detection technique in the temperature interval where the easy magnetization direction of the samples is parallel to the c axis. It is found that an annealing treatment of the as-cast ingots of the RFe10Mo2 compounds at high temperature (at least 1323 K) for a long time (at least two weeks) is vital to obtain RFe10Mo2 compounds with the tetragonal ThMn12 structure. © 1995 The American Physical Society.