Structure and magnetism in Sr A_xTcO 3 perovskites: 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 temperature by x-ray and neutron powder diffraction. The refined Tc moments at room temperature and Néel 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 Néel 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.©2017 American Physical Society