Ferromagnetic tendency at the surface of CE charge-ordered manganites

Abstract

Most previous investigations have shown that the surface of a ferromagnetic material may have antiferromagnetic tendencies. However, experimentally the opposite effect has been recently observed: ferromagnetism appears in some nano-sized manganites with a composition such that the antiferromagnetic charge-ordered CE state is observed in the bulk. A possible origin is the development of ferromagnetic correlations at the surface of these small systems. To clarify these puzzling experimental observations, we have studied the two-orbital double-exchange model near half-doping n=0.5, using open boundary conditions to simulate the surface of either bulk or nano-sized manganites. Considering the enhancement of surface charge density due to a possible AO termination (A = trivalent/divalent ion composite, O = oxygen), an unexpected surface phase-separated state emerges when the model is studied using Monte Carlo techniques on small clusters. This tendency suppresses the CE charge ordering and produces a weak ferromagnetic signal that could explain the experimental observations.

8 pages, 5 figures

References in corpus (6)

• Competing Ferromagnetic and Charge-Ordered States in Models for Manganites: the Origin of the CMR Effect
• Charge order suppression and antiferromagnetic to ferromagnetic switch over in Pr_0.5Ca_0.5MnO_3 nanowires
• Insulator to Metal Transition Induced by Disorder in a Model for Manganites
• Dielectrophoresis model for the colossal electroresistance of phase-separated manganites
• Jahn-Teller distortion induced charge-ordering in CE phase of manganites
• Combined Effect of Bond- and Potential-Disorder in Half-Doped Manganites

Cited by in corpus (1)

• Metal-insulator transition in $(LaMn{O}_3{)}_{2n}/(SrMn{O}_3{)}_n$ superlattices