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VIDEO DOI: https://doi.org/10.48448/1kcq-ge53

technical paper

MMM 2022

November 07, 2022

Minneapolis, United States

A type II multiferroic in two dimensions

Multiferroic materials have garnered wide interest for their exceptional static and dynamical magnetoelectric properties (1). In particular, type-II multiferroics exhibit an inversion-symmetry-breaking magnetic order which directly induces a ferroelectric polarization through various mechanisms, such as the spin-current or the inverse Dzyaloshinskii-Moriya effect. This intrinsic coupling between the magnetic and dipolar order parameters results in record-strength magnetoelectric effects (2). In this context, there has been a recent surge of interest in 2D materials possessing such intrinsic multiferroic properties, enabling the integration and control of magnetoelectric effects in artificial heterostructures and nanoelectronic devices (3,4). In this talk, I will present our recent study and realization of type-II multiferroic order in a single atomic layer of the transition metal-based van der Waals material NiI2 (5). The multiferroic state of NiI2 is characterized by an inversion-symmetry-breaking helimagnetic order which induces a chirality-dependent electrical polarization. Using circular dichroic Raman measurements, we directly probed the magneto-chiral ground state and its electromagnon modes originating from dynamic magnetoelectric coupling. Using birefringence and second-harmonic generation measurements, we observed a highly anisotropic electronic state simultaneously breaking three-fold rotational and inversion symmetry to support polar order. The evolution of the optical signatures as a function of temperature and layer number surprisingly revealed an ordered magnetic, polar state that persists down to the ultrathin limit of monolayer NiI2 (6).

(1) Matsukura, F., Tokura, Y. and Ohno, H. Control of magnetism by electric fields. Nat. Nanotech. 10, 209 (2015).
(2) Spaldin, N. A. and Ramesh, R. Advances in magnetoelectric multiferroics. Nat. Mater. 18, 203 (2019).
(3) Huang, B. et al. Electrical control of 2D magnetism in bilayer CrI3. Nat. Nanotech. 13, 544 (2018).
(4) Jiang, S., Li, L., Wang, Z., Mak, K. F. and Shan, J. Controlling magnetism in 2D CrI3 by electrostatic doping. Nat. Nanotech. 13, 549 (2018).
(5) Kurumaji, T. et al. Magnetoelectric responses induced by domain rearrangement and spin structural change in triangular-lattice helimagnets NiI2 and CoI2. Phys. Rev. B 87, 014429 (2013).
(6) Song, Q. et al. Evidence for a single-layer van der Waals multiferroic. Nature 602, 601 (2022)


Transcript English (automatic)

Next from MMM 2022

Inducing ferroelectricity in NH4I via doping of deuterons, bromide and potassium
technical paper

Inducing ferroelectricity in NH4I via doping of deuterons, bromide and potassium

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+2Lei Meng
Miao Miao Zhao and 4 other authors

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