2008/05/31 by Shuai Dong, Rong Yu, Seiji Yunoki +3
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Electronic and Structural Properties of Oxides #Magnetic and transport properties of perovskites and related materials #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.064414
published as Phys. Rev. B 78 064414 (2008) · 8 pages, 5 figures
arxiv created 2008/07/10 · openalex publication_date 2008/08/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
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 nanosized 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 nanosized 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.