Structure and Magnetism in Sr1-xAxTcO3 Perovskites. The importance of the A-site cation.

Abstract

The Sr1-xBaxTcO3 (x = 0, 0.1, 0.2) oxides were prepared and their solid-state and magnetic structure studied as a function of the temperature by x-ray and neutron powder diffraction. The refined Tc moments at room temperature and Nèel temperatures for Ba0.1Sr0.9TcO3 and Ba0.2Sr0.8TcO3 were 2.32(14) μβ and 2.11(13) μβ and 714 °C and 702 °C respectively. In contrast to expectations, the Nèel temperature in the series Sr1-xAxTcO3 decreases with increasing Ba content. This observation is consistent with previous experimental measurements for the two series AMO3 (M = Ru, Mn; A = Ca, Sr, Ba) where the maximum magnetic ordering temperature was observed for A = Sr. Taken with these previous results the current work demonstrates the critical role of the A-site cation in the broadening of the π* bandwidth and ultimately the magnetic ordering temperature.