Tunable Strong Magnetic Anisotropy in Two-Dimensional van der Waals Antiferromagnets

Abstract

We show that the anisotropic energy of a 2D antiferromagnet is greatly enhanced via stacking on a magnetic substrate layer, arising from the sublattice-dependent interlayer magnetic interaction that defines an effective anisotropic energy. Interestingly, this effective energy couples strongly with the interlayer stacking order and the magnetic order of the substrate layer, providing unique mechanical and magnetic means to control the antiferromagnetic order. These two types of control methods distinctly affect the sublattice magnetization dynamics, with a change in the ratio of sublattice precession amplitudes in the former and its chirality in the latter. In moirésuperlattices formed by a relative twist or strain between the layers, the coupling with stacking order introduces a landscape of effective anisotropic energy across the moire, which can be utilized to create nonuniform antiferromagnetic textures featuring periodically localized low-energy magnons.

Direct correlation between spin states and magnetic torques in a room-temperature van der Waals antiferromagnet

“…Unlike conventional methods, such as vibrating sample magnetometry, the magnetic torque measurement method has been developed to adequately observe the angular dependence of magnetic properties and detect tiny torque variations with extreme sensitivity 36 . Thus, it seems appropriate for examining vdW magnets with highly anisotropic magnetic properties inherently implicated by their 2D nature [37][38][39] . A certain axial or planar magnetic anisotropy incorporated in an antiferromagnet strongly affects the relative angle deviation between the spin and magnetic field orientations, which leads to a certain value of the magnetic torque.…”

Designing Layered 2D Skyrmion Lattices in Moiré Magnetic Heterostructures

“…So far, theoretical studies on moiré magnetic heterostructures are limited to a specific setup, namely an FM monolayer on an AFM substrate (or vice versa), investigated within the single-layer approximation (the substrate spins are assumed fixed). [26,28,35,51] Meanwhile, enormous opportunities exist to construct moiré heterostructures from the rapidly expanding family of 2D magnets, generating a vast unexplored arena for moiré-engineered magnetism. Recent experiments on pristine (untwisted) magnetic heterostructures reported exciting magnetic observations like the emergence of the magnetic proximity effect and interfacial NN DMI.…”

Temperature-Induced Magnonic Chern Insulator in Collinear Antiferromagnets

“…1. We here assume a nearest-neighboring exchange anisotropy, sublattice asymmetric easy-axis anisotropy and nextnearest-neighboring (NNN) interactions, which could be induced and tuned by the substrate, adatoms or in heterostructures [40][41][42]. The spin Hamiltonian is given by…”