Manipulation of magnetic topological textures via perpendicular strain and polarization in van der Waals magnetoelectric heterostructures

The multifunctional manipulation of magnetic topological textures such as skyrmions and bimerons in energy-efficient ways is of great importance for spintronic applications, but it is still a big challenge. Here, by first-principles calculations and atomistic simulations, the creation and annihilation of skyrmions/bimerons, as key operations for the reading and writing of information in spintronic devices, are achieved in a van der Waals magnetoelectric $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure via perpendicular strain or electric field without an external magnetic field. In addition, bimeron-skyrmion conversion, size modulation, and reversible magnetization switching from in plane to out of plane could also be realized in magnetic-field-free ways. Moreover, the topological charge and morphology can be precisely controlled by a small magnetic field. The strong Dzyaloshinskii-Moriya interaction and tunable magnetic anisotropy energy in a wide window are found to play vital roles in such energy-efficient multifunctional manipulation, and the underlying physical mechanisms are elucidated. Our work predicts the $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure to be an ideal platform to address this challenge in spintronic applications, and theoretically guides the low-dissipation multifunctional manipulation of magnetic topological textures.

Figure 1

(a) Top and (b) side views of the $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure. The black dotted lines in (a) show the primitive cell, and the interlayer distance $L$ is defined as the distance between the atomic planes of I and ${\mathrm{Se}}_2$ as shown in (b).

Figure 2

(a) MAE and the energy of the unit cell ($E_{\text{u.c.}}$), (b) atom-resolved SOC energy associated with MAE ($\mathrm{\Delta }{E}_{\mathrm{SOC}\text{−}\mathrm{MAE}}$), (c) DMI, and (d) atom-resolved SOC energy associated with DMI ($\mathrm{\Delta }{E}_{\mathrm{SOC}\text{−}\mathrm{DMI}}$) as functions of the interlayer distance $L$. The optimal interlayer distance $L_0=3.15$ Å is indicated by blue dotted lines in (a)–(d). The inset of (c) demonstrates the in-plane components of DMI between the nearest-neighboring Cr atoms.

Figure 3

(a)–(e) Magnetic-field-free spin textures of $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure with different interlayer distances $L$. (f) and (g) enlarge the framed bimeron and skyrmion in (b) and (d).

Figure 4

Compression-induced conversion from skyrmions to bimerons with controllable topological charge and polarity. (a), (c), and (d) $Q=-1$, and (b), (e), and (f) $Q=1$. The black arrows in (c)–(f) indicate the polarity of bimerons ($\vec{p}$), which is a unit vector from the center of spin down to the center of spin up. The color map is the same as that of Fig. 3.

Figure 5

Regulation of MAE and magnetic topological textures by polarization. (a) MAE of the $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ heterostructure with opposite polarization of the ${\mathrm{In}}_2{\mathrm{Se}}_3$ layer as a function of interlayer distance $L$. (b) The enlarged range of $L$ where the magnetic anisotropy can be tuned between the easy axis and easy plane by polarization. The round and square points in (b) correspond to the results by DFT and interpolation, respectively. (c)–(h) Magnetic-field-free spin textures of $\mathrm{CrISe}\text{/}{\mathrm{In}}_2{\mathrm{Se}}_3$ with the polarization of ${\mathrm{In}}_2{\mathrm{Se}}_3$ along $+Z$ [(c)–(e)] and $-Z$ [(f)–(h)]. $L$ are 2.63 Å [(c), (f)], 2.77 Å [(d), (g)], and 3.88 Å [(e), (h)], respectively. The color map of (c)–(h) is the same as that of Fig. 3.