Hybrid Improper Ferroelectricity in Multiferroic Superlattices: Finite‐Temperature Properties and Electric‐Field‐Driven Switching of Polarization and Magnetization |
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| Authors: | Bin Xu Dawei Wang Hong Jian Zhao Jorge Íñiguez Xiang Ming Chen Laurent Bellaiche |
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| Affiliation: | 1. Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas, USA;2. Electronic Materials Research Laboratory‐Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an, China;3. Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, China;4. Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts‐Fourneaux, L‐4362 Esch/Alzette, Luxembourg, and Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC), Campus UAB, Bellaterra, Spain |
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| Abstract: | The so‐called hybrid improper ferroelectricity (HIF) mechanism allows to create an electrical polarization by assembling two nonpolar materials within a superlattice. It may also lead to the control of the magnetization by an electric field when these two nonpolar materials are magnetic in nature, which is promising for the design of novel magneto‐electric devices. However, several issues of fundamental and technological importance are presently unknown in these hybrid improper ferroelectrics. Examples include the behaviors of its polarization and dielectric response with temperature, and the paths to switch both the polarization and magnetization under electric fields. Here, an effective Hamiltonian scheme is used to study the multiferroic properties of the model superlattice (BiFeO3)1/(NdFeO3)1. Along with the development of a novel Landau‐type potential, this approach allows to answer and understand all the aforementioned issues at both microscopic and macroscopic levels. In particular, the polarization and dielectric response are both found to adopt temperature dependences, close to the phase transition, that agree with the behavior expected for first‐order improper ferroelectrics. And most importantly, a five‐state path resulting in the switching of polarization and magnetization under an electric field, via the reversal of antiphase octahedral tiltings, is also identified. |
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| Keywords: | effective Hamiltonian improper hybrid ferroelectricity multiferroics superlattices switching mechanism |
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