Multiferroicity in vanadium-doped La2Ti2O7: insights from first principles*
CNR-IOM, UOS Cagliari, and Department of Physics,
University of Cagliari, Cittadella Universitaria, 09042
Monserrato ( CA), Italy
Received in final form: 18 December 2012
Published online: 4 April 2013
We explore an unconventional route in the search for multiferroicity investigating the magnetic doping of La2Ti2O7 (LTO), a ferroelectric layered perovskite, by density functional calculations. We find that substitution of Ti (in the 3d0 configuration) by V (3d1) produces: (i) robust ferromagnetic (FM) order, achieving multiferroicity; (ii) structural and magnetic anisotropy, as the dopants cluster in magnetic chains. Moreover, the FM V-chains possess antiferro orbital ordering. We show that the origin of the strong FM coupling lies in the fruitful host-dopant combination: the layered structure of the host prewires the orbitals t2g with dxy and dxz lower in energy, the V dopants provide the full occupancy of the bonding levels. We further address the stability of chains vs. temperature and the role of oxygen vacancies in undoped as well as Sc-doped and V-doped LTO.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2013