Table of Contents
Physics Research International
Volume 2012, Article ID 632016, 7 pages
http://dx.doi.org/10.1155/2012/632016
Research Article

Metamagnetic Phase Transitions in ( 𝐒 𝐦 𝟎 . 𝟓 𝐆 𝐝 𝟎 . 𝟓 ) 𝟎 . 𝟓 𝟓 𝐒 𝐫 𝟎 . 𝟒 𝟓 𝐌 𝐧 𝐎 𝟑 Ceramics

Department of Electronic Properties of Metals, Donetsk Physical and Technical Institute NASU, Donetsk 83114, Ukraine

Received 4 August 2011; Revised 18 January 2012; Accepted 18 January 2012

Academic Editor: Manh-Huong Phan

Copyright © 2012 Fedor N. Bukhanko. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The temperature dependences of ac magnetic susceptibility of the (Sm0.5Gd0.5)0.55Sr0.45MnO3 ceramics provide evidence of the formation of a mixed insulating state with a specific quantum-disordered phase, in which the domains with a long-range antiferromagnetic order dominate at temperatures below 𝑇 N ≅ 4 8 , 5  K. Irreversible metamagnetic phase transition in the ferromagnetically ordered state is carried out at the critical field 𝐻 c 1 ∼ 2 5  kOe which remains constant in the temperature range from 4.2 K to 60 K. From the analysis of the magnetization isotherms, the conclusion can be made about a spontaneous phase transition into the state with charge and orbital ordering at temperatures below the critical value 𝑇 C O ∼ 6 0  K. It is supposed that short-range charge correlations exist in unusually large interval of temperatures ~90 K at temperatures above 𝑇 C O that considerably exceeds the area of existence of local orbital correlations ~50 K.