Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 25: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles II (jointly with TT)

O 25.7: Vortrag

Dienstag, 27. März 2012, 12:15–12:30, HE 101

Pressure driven half-metallic ferromagnetism and magnetic moment collapse in LaMnO₃: a hybrid functional study — •Jiangang He and Cesare Franchini — University of Vienna, Faculty of Physics and Center for Computational Materials Science, A-1090 Vienna, Austria

The application of hydrostatic pressure to the antiferromagnetic and insulating e_g perovskite LaMnO₃ induces an electronic structure transition towards a metallic state at ≈ 34 GPa, and a progressive quenching of the underlying Jahn-Teller structural distortions [1,2]. By means of the Heyd, Scuseria, and Ernzerhof (HSE) screened hybrid functional approach we outline the evolution of the structural, electronic, and magnetic properties of LaMnO₃ in the pressure range 0−140 GPa. Beside providing an atomistic understanding of the observed insulator-to-metal transition we predict the formation of a transport half-metal ferromagnetic cubic phase at elevated pressure (> 80 GPa), associated with a high-spin (S=2, 3.7 µ_B) to low-spin (S=1, 1.7 µ_B) magnetic moment collapse, and characterized by a significantly large spin polarization (I ≈ 80−90 %). Our results open up the possibility of realizing colossal magnetoresistance behaviours in a stoichiometric manganite.

References:

[1] I. Loa et al. Phys. Rev. Lett. 87, 125501 (2001);

M. Baldini et al. Phys. Rev. Lett. 106, 066402 (2011).

[2] G. Trimarchi and N. Binggeli, Phys. Rev. B 71, 035101 (2005);

A. Yamasaki et al. Phys. Rev. Lett. 96, 166401 (2006).