Determination of the easy axis of magnetization in terbium-yttrium iron garnet Tb1Y2Fe5O12 at low temperatures

摘要

Experimental investigations have been carried out on a spherical single crystal of terbium yttrium iron garnet (Tb1Y2Fe5O12) by means of magnetization measurements in strong dc magnetic fields up to 200 kOe applied along the < 111 >, < 110 > and < 100 > crystallographic directions at low temperatures (T < 20 K) with a high degree of resolution both in field and temperature. The strong anisotropic magnetic behavior which appears at 4.2 K is due to the competition between < 111 > and < 100 > directions to be the easy axis of spontaneous magnetization while the < 110 > clirection remains the more difficult axis. The magnetization measurement at 4.2 K leaving the sample to rotate freely on itself suggests that the easy axis of spontaneous magnetization is along the < 100 > direction. However, due to the magnetic anisotropy energies associated vvith both < 100 > and <111 > directions which are close to each other, the phase <111 > becomes more stable as soon as the magnetic field exceeds 10 kOe or the temperature is higher than 10 K. The results are compared vvith previous works. (C) 2015 Elsevier B.V. All rights reserved.