Magnetic properties of Tm2Fe17-xSix alloys

Abstract

The cell parameters and magnetic properties of alloys with approximate composition Tm 2 Fe 17-x Si x and various Tm:(Fe+Si) ratios are reported. All the investigated compounds were found to crystallize in the hexagonal Th 2 Ni 17 type. The magnetic properties of polycrystalline samples were investigated in the temperature range 1.9-1100 K in various magnetic fields. The field dependence of the magnetization was studied at T = 4.2 and 77 K in a steady magnetic field up to 14 T, and additionally in a pulsed magnetic field up to 36 T at T = 4.2 K with a pulse duration of 10 ms. The temperature dependence of the magnetization of the alloys exhibits pronounced maxima located at various temperatures, most probably related to spin reorientation and other magnetic anomalies. These anomalies seem to indicate also ferrimagnetic character of the magnetic order, resulting from opposite directions of the magnetic moments of Fe and Tm in the investigated compounds. Additional confirmation of this supposition is the lack of substantial difference between ZFC (zero-field cooled) and FC (field cooled) runs, and the absence of full saturation of magnetization, even under the highest magnetic field. The Néel (Curie) temperatures determined from the dM/dT plots amount to 383 K for x = 0 and 466 K for x = 3. For the saturation magnetic moment in a magnetic field of about 35 T at T = 4.2 K the opposite tendency is observed. The highest value was determined for pristine Tm 2.1 Fe 17.9 (M s = 35.2 µ B) and the lowest value for Tm 2.1 Fe 14.9 Si 3. Ternary rare-earth silicides / Magnetic properties / Magnetic phase transitions / High-magnetic field measurements