MultiferroicBiFeO3-BiMnO3nanoscale checkerboard from first principles

Abstract

We present a first principles study of an unusual heterostructure, an atomic-scale checkerboard of BiFeO3-BiMnO3, and compare its properties to the two bulk constituent materials, BiFeO3 and BiMnO3. The "nanocheckerboard" is found to have a multiferroic ground state with the desired properties of each constituent: polar and ferrimagnetic due to BiFeO3 and BiMnO3, respectively. The effect of B-site cation ordering on magnetic ordering in the BiFeO3-BiMnO3 system is studied. The checkerboard geometry is seen to give rise to a a novel magnetostructural effect that is neither present in the bulk constituent materials, nor in the layered BiFeO3-BiMnO3 superlattice.

Interface‐Coupled BiFeO3/BiMnO3 Superlattices with Magnetic Transition Temperature up to 410 K

“…SL-BFO/BMO fi lms have the same lowest energy magnetic ordering as NCB-BFO/BMO: ferrimagnetic ordering of AFM-Fe and FM-Mn (Figure 4 c). [ 10 ] The absence of T C2 for m = 4, 8 superlattices is consistent with the increasing out-of-plane lattice parameter in BFO structure with increasing m , and the separation of BFO and BMO into two distinct lattices ( Figures 2 and 3 c) rather than a single strain BFO-BMO lattice. Here, the distortions of the B O 6 octahedra at the BMO/ BFO interfaces may be not suitable for optimum magnetic coupling.…”

“…[ 10 ] The high T C2 of up to 410 K in our very short period SL-BFO/BMO is very close to this predicted T C . SL-BFO/BMO fi lms have the same lowest energy magnetic ordering as NCB-BFO/BMO: ferrimagnetic ordering of AFM-Fe and FM-Mn (Figure 4 c).…”

“…In this structure, small local variations in magnetic behavior will also be expected since the number of Fe-Mn nearest neighbors is halved for a 1:1 SL-BFO/BMO compared to NCB-BFO/BMO. [ 10 ] Various studies on short period perovskite superlattices have shown that the magnetic behavior can be enhanced by the interaction between the B -site cations. For example, Ueda et al reported ferromagnetism at 375 and 230 K in (111)-oriented…”

“…[ 16,17 ] Pálová et al extended the idea of ordered double perovskites by theoretically studying BFMO with an ordered nanoscale checkerboard structure (NCB-BFO/BMO, see Figure 1 a), i.e., columnar B -site ordering. [ 10 ] Their calculations predict that an ordered NCB-BFO/BMO would be ferroelectric and ferrimagnetic (FiM) with M S of 3.8 µ B /Fe-Mn pair and T C of 406 K, as a result of magnetic ordering arising from the superexchange coupling between the neighboring AFM-Fe and FM-Mn. [ 10 ] Unfortunately, spontaneous columnar B -site ordering is not expected and high quality growth of artifi cial 1:1 BFO/BMO superlattices along the 〈110〉 direction is very hard.…”

“…[ 6 ] With strong ferromagnetic behavior in BMO and strong ferroelectric behavior in BFO, various studies have suggested combining BMO and BFO in order to achieve room-temperature (RT) multiferroicity. [7][8][9][10] One approach is to modify the local spin confi guration of Fe by chemical doping at the B -site. [ 8,9 ] By 50% doping, this simple concept could result in ordered double perovskite ferrites of Bi 3+ 2 Fe…”