Frustrated ferromagnetic transition in AB-stacked honeycomb bilayer

Wang, S. Y.; Wang, Y.; Yan, Shaohua; Wang, C.; Xiang, Boyuan; Liang, Kun; He, Qing; Watanabe, Kenji; Taniguchi, Takashi; Tian, Shangjie; Lei, Hechang; Ji, Weike; Qi, Yang; Wang, Y. H.

doi:10.1016/j.scib.2022.12.009

Cited by 3 publications

(2 citation statements)

References 45 publications

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“…子体系中自旋轨道耦合的作用，破坏了晶格的空间反演对称性 [51] 。由于本文仅在线性自旋波近似下进行研究，因此忽略了对系统哈密顿量影响较小的最近邻 DM 相互作用项。第四项表示易轴各向异性相互作用引起的能量 [52,53]…”

Section: H J S S J S S D S S S S H S H J S S J S S D S S S S H S H J ...unclassified

Effect of interlayer exchange coupling interaction on topological phase of a bilayer honeycomb Heisenberg ferromagnet

Shi,

Tang,

Liu

2024

Acta Phys. Sin.

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Layered magnetic topological materials are systems that exhibit both magnetic ordering and topological properties within their smallest two-dimensional units. The study of these systems may lead to the observation of new physical properties and phenomena, thereby garnering considerable interest among researchers. The effect of interlayer exchange coupling interactions on bilayer honeycomb Heisenberg ferromagnets with interlayer coupled topological phases has been investigated using linear spin wave theory. The impact of introducing two additional types of interlayer exchange coupling interactions and interlayer easy-axis anisotropy interactions on the topological phase transition are also explored in this work. By calculating the magnon dispersion relations at various interlayer exchange coupling interaction intensities, it was found that the band gaps of both high and low energy bands close and reopen at the Dirac points when the system reaches the critical values of the interlayer exchange coupling interactions. In magnon systems, such physical phenomena are typically associated with topological phase transitions. Upon calculating the Berry curvature and Chern numbers for the bands in the aforementioned process, it was discovered that the sign of the Berry curvature reverses and the Chern numbers change once the critical values of interlayer exchange coupling interaction strengths are reached, confirming that a topological phase transition has indeed occurred. Introducing two other types of interlayer exchange coupling interactions in this process can lead to the emergence of various novel topological phases within the system. The enhancement of interlayer easy-axis anisotropy interactions is likely to impede the occurrence of topological phase transitions in the system. We have found that a major distinction between bilayer honeycomb ferromagnets and their single-layer counterparts is that the sign of the magnon thermal Hall coefficient does not change during a topological phase transition; rather, abrupt shifts in the thermal Hall coefficient curve can be seen as indicators of topological phase transitions in bilayer honeycomb ferromagnets, which is also reflected in the changes in magnon Nernst coefficients. The research outcomes of this work can provide theoretical support for the development of novel spintronic devices with enhanced information transmission capabilities using bilayer honeycomb ferromagnetic materials, as well as serve as a theoretical reference for studies on other bilayer ferromagnetic systems.

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Section: H J S S J S S D S S S S H S H J S S J S S D S S S S H S H J ...unclassified

Effect of interlayer exchange coupling interaction on topological phase of a bilayer honeycomb Heisenberg ferromagnet

Shi,

Tang,

Liu

2024

Acta Phys. Sin.

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“…This is important for studies of samples with small volumes, especially two-dimensional quantum materials and quantum devices fabricated from these materials 8 . While the direct flux sensitivities of nano-SQUIDs are useful in imaging physical quantities such as the magnetization of a ferromagnet, the vortex in a superconductor 9 , 10 or the edge current in a quantum spin Hall insulator 11 , susceptometry 12 – 15 is indispensable for probing spin correlations 16 or superfluid densities 17 – 19 , which are not observable with magnetometry.…”

Section: Introductionmentioning

confidence: 99%

Flux focusing with a superconducting nanoneedle for scanning SQUID susceptometry

Xiang

Wang

et al. 2023

Microsyst Nanoeng

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A nanofabricated superconducting quantum interference device (nano-SQUID) is a direct and sensitive flux probe used for magnetic imaging of quantum materials and mesoscopic devices. Due to the functionalities of superconductive integrated circuits, nano-SQUIDs fabricated on chips are particularly versatile, but their spatial resolution has been limited by their planar geometries. Here, we use femtosecond laser 3-dimensional (3D) lithography to print a needle onto a nano-SQUID susceptometer to overcome the limits of the planar structure. The nanoneedle coated with a superconducting shell focused the flux from both the field coil and the sample. We performed scanning imaging with such a needle-on-SQUID (NoS) device on superconducting test patterns with topographic feedback. The NoS showed improved spatial resolution in both magnetometry and susceptometry relative to the planarized counterpart. This work serves as a proof-of-principle for integration and inductive coupling between superconducting 3D nanostructures and on-chip Josephson nanodevices.

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Fabrication and Application of Nano-SQUID Magnetometer to Scanning Imaging of Two-Dimensional Quantum Materials

Xiang,

Wang,

et al. 2024

Electromag. Sci.

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Frustrated ferromagnetic transition in AB-stacked honeycomb bilayer

Cited by 3 publications

References 45 publications

Effect of interlayer exchange coupling interaction on topological phase of a bilayer honeycomb Heisenberg ferromagnet

Effect of interlayer exchange coupling interaction on topological phase of a bilayer honeycomb Heisenberg ferromagnet

Flux focusing with a superconducting nanoneedle for scanning SQUID susceptometry

Fabrication and Application of Nano-SQUID Magnetometer to Scanning Imaging of Two-Dimensional Quantum Materials

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