A Minimal tight-binding model for ferromagnetic canted bilayer manganites

Abstract

Half-metallicity in materials has been a subject of extensive research due to its potential for applications in spintronics. Ferromagnetic manganites have been seen as a good candidate, and aside from a small minority-spin pocket observed in La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$ $(x=0.38)$, transport measurements show that ferromagnetic manganites essentially behave like half metals. Here we develop robust tight-binding models to describe the electronic band structure of the majority as well as minority spin states of ferromagnetic, spin-canted antiferromagnetic, and fully antiferromagnetic bilayer manganites. Both the bilayer coupling between the MnO${}_2$ planes and the mixing of the $|x^2-y^2>$ and $|3z^2-r^2>$ Mn 3d orbitals play an important role in the subtle behavior of the bilayer splitting. Effects of $k_z$ dispersion are included.

18 pages, and 6 figures

References in corpus (3)

• Structural distortions and model Hamiltonian parameters: from LSDA to a tight-binding description of LaMnO_3
• Role of Oxygen Electrons in the Metal-Insulator Transition in the Magnetoresistive Oxide La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$ Probed by Compton Scattering
• Orbital mixing and nesting in the bilayer manganites La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$