Magneto-optical Kerr Effect of Mono-layer NiX₂(X=Cl, Br, I): A Density Functional Theory Study

Abstract

The full-potential linearized augmented plane wave plus local orbital method is utilized for exploring the electronic, magnetic, and magneto-optical properties of the NiX₂ (X=Cl, Br, and I) single layer. The first-principles calculation demonstrates that these compounds are ferromagnetic indirect semiconductors, and the energy band gaps of NiX₂ for X=Cl, Br, and I are 3.888, 3.134, and 2.157 eV, respectively. The magnetic moments of Ni atoms in NiX₂ monolayer are 1.656, 1.588, 1.449 µB, and their magneto-crystalline anisotropy energies are 0.167, 0.029, 0.090 meV, respectively. Based on the macro-linear response theory, we systematically studied the influences of the external magnetic field and out-of-plane strain on the magneto-optical Kerr effect (MOKE) spectrum of the NiX₂ single layer. It is found that, when the external magnetic field is perpendicular to the sample plane, the value of the Kerr rotation angle reaches the maximum, and the single-layer NiI₂ material has a Kerr rotation angle of 1.89° at the photon energy of 1.986 eV. Besides, the Kerr rotation spectrum of NiCl₂ and NiBr₂ monolayers redshift as the out-of-plane strain increases, while NiI₂ monolayer blueshifts. Accurate computation of the MOKE spectrum of NiX₂ materials provides an opportunity for applications of 2D magnetic material ranging from sensing to data storing.

Keywords

magneto-optical Kerr effect (MOKE) / first-principles calculations / external magnetic field / out-of-plane strain

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