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Switching between Skyrmions and Yoshimori Spin Spirals via Li Absorption in Janus Magnets

Xinyuan Jiang, Jian Wu, Weiyi Pan

TL;DR

Probing how Li adsorption on Se- versus Te-terminated surfaces of Janus CrTeSe switches between Yoshimori-type spin spirals and skyrmions, this work combines first-principles calculations and atomic spin-dynamics simulations to link texture stability to site-dependent changes in exchange interactions, magnetic anisotropy, and the Dzyaloshinskii–Moriya interaction. First-principles calculations establish adsorption energetics, structural changes, and magnetic parameters for LiCrTeSe on both surfaces, mapping to a spin Hamiltonian with $J_1$, $J_2$, $J_3$, $A$, and $oldsymbol{D}_{ij}$. Spin-dynamics simulations confirm LiCrTeSe-1 hosts a Yoshimori spiral with a period of $27.19$ Å whereas LiCrTeSe-2 forms an isolated skyrmion of radius $48.34$ Å, with DMI tuning chirality and exchange-frustration driving the textures. Under external out-of-plane fields, LiCrTeSe-1 shows remarkable spiral robustness up to ~$150$ T before nucleating skyrmions around ~$200$ T, while LiCrTeSe-2 forms isolated skyrmions at ~20 T, highlighting distinct field sensitivities. Overall, the study demonstrates a feasible surface adsorption route to reversibly switch chiral magnetic textures in 2D Janus magnets, with implications for tunable spintronic devices.

Abstract

Chiral magnetic textures have attracted considerable attention owing to their topological properties and potential applications in spintronic devices. Here, we employ first-principles calculations together with atomic spin dynamics simulations to explore the switching between skyrmions and Yoshimori-type spin spirals induced by Li adsorption in Janus two-dimensional (2D) CrTeSe. We show that selective Li adsorption on either the Se- or Te-terminated surface stabilizes distinct magnetic phases: Li adsorption on the Se side favors a Yoshimori-type spin spiral, whereas adsorption on the Te side stabilizes the skyrmionic state. This contrast originates from site-dependent modifications of exchange interactions, magnetic anisotropy (MA), and the Dzyaloshinskii-Moriya interaction (DMI). In addition, the response of magnetic textures to out-of-plane magnetic fields differs strongly between the two systems. These results demonstrate that surface adsorption provides an effective strategy for reversible control of chiral magnetic states in 2D magnets, while also offering fundamental insights into the competing interactions that govern the stability of skyrmions and Yoshimori spin spirals. Our findings highlight the potential of Janus 2D materials as a versatile platform for engineering tunable spintronic devices.

Switching between Skyrmions and Yoshimori Spin Spirals via Li Absorption in Janus Magnets

TL;DR

Probing how Li adsorption on Se- versus Te-terminated surfaces of Janus CrTeSe switches between Yoshimori-type spin spirals and skyrmions, this work combines first-principles calculations and atomic spin-dynamics simulations to link texture stability to site-dependent changes in exchange interactions, magnetic anisotropy, and the Dzyaloshinskii–Moriya interaction. First-principles calculations establish adsorption energetics, structural changes, and magnetic parameters for LiCrTeSe on both surfaces, mapping to a spin Hamiltonian with , , , , and . Spin-dynamics simulations confirm LiCrTeSe-1 hosts a Yoshimori spiral with a period of Å whereas LiCrTeSe-2 forms an isolated skyrmion of radius Å, with DMI tuning chirality and exchange-frustration driving the textures. Under external out-of-plane fields, LiCrTeSe-1 shows remarkable spiral robustness up to ~ T before nucleating skyrmions around ~ T, while LiCrTeSe-2 forms isolated skyrmions at ~20 T, highlighting distinct field sensitivities. Overall, the study demonstrates a feasible surface adsorption route to reversibly switch chiral magnetic textures in 2D Janus magnets, with implications for tunable spintronic devices.

Abstract

Chiral magnetic textures have attracted considerable attention owing to their topological properties and potential applications in spintronic devices. Here, we employ first-principles calculations together with atomic spin dynamics simulations to explore the switching between skyrmions and Yoshimori-type spin spirals induced by Li adsorption in Janus two-dimensional (2D) CrTeSe. We show that selective Li adsorption on either the Se- or Te-terminated surface stabilizes distinct magnetic phases: Li adsorption on the Se side favors a Yoshimori-type spin spiral, whereas adsorption on the Te side stabilizes the skyrmionic state. This contrast originates from site-dependent modifications of exchange interactions, magnetic anisotropy (MA), and the Dzyaloshinskii-Moriya interaction (DMI). In addition, the response of magnetic textures to out-of-plane magnetic fields differs strongly between the two systems. These results demonstrate that surface adsorption provides an effective strategy for reversible control of chiral magnetic states in 2D magnets, while also offering fundamental insights into the competing interactions that govern the stability of skyrmions and Yoshimori spin spirals. Our findings highlight the potential of Janus 2D materials as a versatile platform for engineering tunable spintronic devices.
Paper Structure (9 sections, 6 equations, 4 figures, 2 tables)

This paper contains 9 sections, 6 equations, 4 figures, 2 tables.

Table of Contents

  1. INTRODUCTION
  2. METHODS
  3. First Principle Calculation
  4. LLG Simulations
  5. RESULTS AND DISCUSSION
  6. Electronic and magnetic properties
  7. Magnetic Phase Diagram
  8. Magnetic textures under external magnetic field
  9. CONCLUSION

Figures (4)

  • Figure 1: (a1)-(a2) Crystal structures of LiCrTeSe-1 and LiCrTeSe-2, respectively. For each structure, the upper panel shows the top view along the $z$-axis, and the lower panel presents the side view perpendicular to the $z$-axis. (b1)-(b2) Phonon spectra of LiCrTeSe-1 and LiCrTeSe-2, respectively. (c) Schematic representation of Heisenberg exchange interactions, with first-nearest neighbor $J_1$, second-nearest neighbor $J_2$, and third-nearest neighbor $J_3$. (d) Schematic of four distinct magnetic configurations constructed to calculate the Heisenberg exchange parameters. In the diagram, red spheres represent atoms in the spin-up state and blue spheres represent atoms in the spin-down state.
  • Figure 2: The color map indicates the out-of-plane spin component. (a) Magnetic ground states of LiCrTeSe-1. The left panel presents the overall magnetic configuration, while the right panel shows a magnified view of the red boxed region. This magnified view reveals a Yoshimori spin spiral with a period of 27.19 Å (corresponding to seven lattice constants). (b) Magnetic ground state of LiCrTeSe-2. The left panel displays the global magnetic structure, and the right panel provides a magnified view of the red boxed region. This enlarged view highlights an isolated skyrmion with a radius of 48.34 Å (corresponding to twelve lattice constants).
  • Figure 3: The color map indicates the out-of-plane spin component. (a) Phase diagram of the toy model with parameters $J_1=-20$ meV/Cr (FM), $d_{//}=4$ meV/Cr, $A=2$ meV/Cr (IMA), and $J_2=0$, while tuning $J_3$ from 0 to 16 meV/Cr (AFM). (b) Phase diagram of the toy model with parameters $J_1=-20$ meV/Cr (FM), $A=2$ meV/Cr (IMA), $J_2=0$, and $J_3=8$ meV/Cr (AFM), while varying $d_{//}$ from 0 to 8 meV/Cr. (c) Phase diagram of the toy model obtained by fixing $J_1=-20$ meV/Cr (FM), $d_{//}=4$ meV/Cr, $J_2=J_3=0$, and varying the anisotropy $A$ from –4 meV/Cr (PMA) to +4 meV/Cr (IMA).
  • Figure 4: The color map indicates the out-of-plane spin component. Magnetic ground state of (a) LiCrTeSe-1 and (b) LiCrTeSe-2 under an external out-of-plane magnetic field $B_z$.