Mixed Phase in the Reentrant Ising System FexMn1-xTiO3

Abstract

Despite a number of experimental reports on the magnetic ion concentration x versus temperature phase diagram on spin glass systems,1) little attention has been paid to the difference between the pure spin glass phase and the reentrant spin glass phase. This is partly because the spin glass phase appears in a very narrow region on the concentration axis, and partly because almost all reentrant spin glass materials belong to the class of the ferromagnetic interaction dominated system, in other words, they reenter to the spin glass phase after establishing the ferromagnetic long range order. The former reason means that the concentration gradient in the sample is crucial in order to perform a reliable study of spin glass behavior as a function of the concentration x. The latter causes the technical difficulty in neutron scattering experiments.2) Since a ferromagnetic Bragg reflection always overlaps with a structual Bragg reflection, it is difficult to obtain definite information on the magnetic long range order. If the system exhibits the antiferromagnetic order, such a difficulty is obviously resolved. Recently A. Ito and coworkers discovered an antiferromagnetism-based spin glass system Fe0.5Mn0.5TiO3, and carried out intensive studies on relaxational phenomena.3)