A New Ferromagnetic Amorphous Oxide of the La-Sr-Mn-B-O System

Abstract

Amorphous 0.5La 1- x Sr x MnO 3 0.5B 2 O 3 (0.2≤ x ≤1.0) oxides were produced by melt quenching using a twin-roll technique. They were characterized by high crystallization temperatures above 920 K and transparency. Curie temperature is higher than 380 K over a wide range of Sr concentrations (0.3≤ x ≤1.0), thus differing from crystalline La 1- x Sr x MnO 3 perovskite. The temperature dependence of magnetization in the amorphous state is similar to that for crystalline perovskite, suggesting ferromagnetism in the present amorphous oxides. The ferromagnetic behavior of the amorphous state may be explained by positive double-exchange interactions of Mn 3+ and Mn 4+ ions.