Novel effects in multiferroic materials

S Omid Sayedaghaee, Bin Xu, Sergey Prosandeev, Charles Paillard, L Bellaiche

Overview

We predicted the existence of a novel quasiparticle called electroacoustic magnon which is a mixture of acoustic phonons, optical phonons, and magnons. This article reveals that the resonances of magnetoelectric responses of multiferroics is subject to change by varying the the frequency of applied magnetic field as well as the size and shape of the material which helps experimentalists and engineers to optimize magnetoelectric devices.

Summary

This is a pioneering work that studies the dynamical magnetoelectric couplings in single phase multiferroics. It provides potentials to design novel devices, specially storage media and memory devices.

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Promising material could lead to faster, cheaper computer memory
https://phys.org/news/2019-05-material-faster-cheaper-memory.html

Novel Dynamical Magnetoelectric Effects in Multiferroic BiFeO_{3}.

Authors:
sayedaghaee, Ph.D. Candidate in Microelectronics-Photonics
sayedaghaee, Ph.D. Candidate in Microelectronics-Photonics
University of Arkansas Fayetteville
Research Assistant
Computational Skills
Fayetteville, AR | United States

Phys Rev Lett 2019 Mar;122(9):097601

Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA.

An atomistic effective Hamiltonian scheme is employed within molecular dynamics simulations to investigate how the electrical polarization and magnetization of the multiferroic BiFeO_{3} respond to time-dependent ac magnetic fields of various frequencies, as well as to reveal the frequency dependency of the dynamical (quadratic) magnetoelectric coefficient. We found the occurrence of vibrations having phonon frequencies in both the time dependency of the electrical polarization and magnetization (for any applied ac frequency), therefore making such vibrations of electromagnonic nature, when the homogeneous strain of the system is frozen (case 1). Moreover, the quadratic magnetoelectric coupling constant is monotonic and almost dispersionless in the sub-THz range in this case 1. In contrast, when the homogeneous strain can fully relax (case 2), two additional low-frequency and strain-mediated oscillations emerge in the time-dependent behavior of the polarization and magnetization, which result in resonances in the quadratic magnetoelectric coefficient. Such additional oscillations consist of a mixing between acoustic phonons, optical phonons, and magnons, and reflect the existence of a new quasiparticle that can be coined an "electroacoustic magnon." This latter finding can prompt experimentalists to shape their samples to take advantage of, and tune, the magnetostrictive-induced mechanical resonance frequency, in order to achieve large dynamical magnetoelectric couplings.

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http://dx.doi.org/10.1103/PhysRevLett.122.097601DOI Listing
March 2019
3 Reads
7.512 Impact Factor

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