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Can the Aurivillius Phases be Multiferroic ? A First Principles Based Study
| Content Provider | Semantic Scholar |
|---|---|
| Author | Troyer, Matthias |
| Copyright Year | 2016 |
| Abstract | Multiferroic materials combining magnetic properties with electric polarisation in the same phase, are promising for novel applications in electronic devices.[1] However, these combined properties are typically exhibited at low temperatures. Novel ways to integrate ferroelectricity with long-range magnetic order above room temperature are therefore of high relevance. We focus on the Aurivillius family of naturally-layered perovskite-related materials, which combine well-established high temperature ferroelectric properties [2, 3] with a layered structure that allows for systematic introduction of various magnetic ions. The structure consists of m perovskite layers (Am 1BmO3m+1) , stacked along the [001] direction, and separated by fluorite-like (Bi2O2) layers. To exhibit robust multiferroic properties, the Aurivillius phases need to satisfy two criteria: i) maintain ferroelectricity despite the introduction of magnetic cations, and ii) form long-range magnetic order from magnetically dilute compositions. The simplest case that has been explored as potential multiferroic is Bi5FeTi3O15. However, no well-established value exists for its spontaneous electric polarisation, with reports varying from 3.5μC/cm2 to ⇠ 30μC/cm2.[4, 5] Similarly, an antiferromagnetic Néel temperature of 80 K has been reported [6], in contradiction with other studies observing paramagnetic behaviour with no magnetic long-range order even at very low temperatures.[4, 7–9] To provide clarification as well as guideline for future studies, we first establish the intrinsic properties of Bi5FeTi3O15 using first-principles electronic structure calculations and symmetry mode analysis. These results are then generalized to other Aurivillius phases. We also perform Monte Carlo simulations to assess the possibility of long-range magnetic order and estimate the corresponding ordering temperature. For the case of Bi5FeTi3O15, we find a slight preference of the Fe3+ cation to occupy the “inner” site within the perovskite-like layers, consistent with recent experimental observations.[10] This site-preference can be tuned by applying epitaxial strain and we observe a transition to an “outer”-site preference under strong in-plane compressive strain. The calculated value for the spontaneous electric polarisation of Bi5FeTi3O15 is ⇠ 55μC/cm2, and can also be tuned by applying epitaxial strain. We obtain very strong antiferromagnetic coupling for |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/117221/eth-48844-02.pdf?isAllowed=y&sequence=2 |
| Alternate Webpage(s) | https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/117221/eth-48844-01.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
