Structural effects in Mn eg orbital occupancy of manganites using the two-orbital modelH. Marks and G. Martínez
Instituto de Física, Universidade Federal do Rio Grande do Sul - 91501-970 Porto Alegre, RS, Brasil
received 16 October 2008; accepted in final form 10 February 2009; published March 2009
published online 17 March 2009
The zero-temperature ferromagnetic phase of distorted perovskite manganites at low doping is studied as a function of lattice parameters and screened ionic charges using the two-orbital model. The dependence in the Mn-O distance of the anisotropic hopping terms is calculated numerically for La1-xSrxMnO3. It is shown that the eg state is dominated by the 3z2 - r2 type orbital. For bandwidths comparable to Hund's rule coupling we find partially spin-polarized eg bands at small doping levels, in agreement with experimental observations using Andreev reflection. We also find small but consistent results for the static Jahn-Teller distortion at small doping. The connection of our solution to electron correlation effects is discussed.
75.47.Lx - Manganites.
75.50.Cc - Other ferromagnetic metals and alloys.
75.25.+z - Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.).
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