Effects of cation size disorder and lattice distortion on metamagnetism in phase-separated manganites

• Published in: Solid state communications 2005-07, Vol.135 (3), p.183-188
• Main Authors: Mavani, K.R., Paulose, P.L.
• Format: Article
• Language: English
• Subjects: A. Manganites; Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Ferromagnetic clusters; D. Metamagnetic transition; Exact sciences and technology; Magnetic properties and materials; Magnetotransport phenomena, materials for magnetotransport; Manganites; Physics; Studies of specific magnetic materials
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2005.04.023

The effects of A-site cation size disorder in ABO 3 type charge-ordered and antiferromagnetic Pr 0.5Ca 0.5MnO 3 system have been studied by substituting La 3+, Sr 2+ or Ba 2+, while keeping the valency of Mn ions and the tolerance factor ( t=0.921) constant in the substituted compounds. We find that the substitutions by these larger cations induce successive sharp step-like metamagnetic transitions at 2.5 K. The critical field for metamagnetism is the lowest for 3% Ba substituted compound, which has the largest A-site cation size disorder and the least distorted MnO 6 octahedra, among the compounds reported here. These cation substitutions give rise to ferromagnetic clusters within antiferromagnetic matrix, indicating phase-separation at low temperatures. The growth of the clusters is found to vary with the substitution amount. The local lattice distortion of MnO 6 octahedra enhances the charge ordering temperature and reduces the magnetization at high fields (>1 T) in these manganites.