Multiferroic properties of the PbTiO3/La2/3Sr1/3MnO3 interface studied from first principles

Magnetoelectric coupling and spin polarization at the multiferroic PbTiO3/La2/3Sr1/3MnO3 (PTO/LSMO) interface is studied from first principles in view of the recent experimental observation of the tunneling magnetoresistance sign inversion in Co/PZT/LSMO tunnel junctions (Pantel et al 2012 Nat. Mater. 11 289). Our results confirm the stabilization of the locally antiferromagnetic order in the manganite when the PTO polarization points away from the LSMO side, which changes the interface magnetization by 6.3-6.9 mu(B) per surface unit cell in agreement with previous studies. We contribute by analyzing the charge transfer from the half-metallic LSMO side which induces metallicity and local magnetic moments in the interface PTO layers. This results in either p- or n-doped conductive behavior, depending on the polarization direction. Electronic correlations were determined to qualitatively change the picture for certain configurations, as far as the magnetic phase transition in the manganite and the spin character of the interface states are concerned. Most importantly, depending on the interface termination, the spin polarization of the PTO/LSMO interface is positive for one polarization state of PTO and acquires a 'spin-valve' character upon the ferroelectric switching.