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1. Mutual control of coherent spin waves and magnetic domain walls in a magnonic device

   https://doi.org/10.1126/science.aau2610  

   Han, Jiahao; Zhang, Pengxiang; Hou, Justin T.; Siddiqui, Saima A.; Liu, Luqiao (November 2019, Science)

   The successful implementation of spin-wave devices requires efficient modulation of spin-wave propagation. Using cobalt/nickel multilayer films, we experimentally demonstrate that nanometer-wide magnetic domain walls can be applied to manipulate the phase and magnitude of coherent spin waves in a nonvolatile manner. We further show that a spin wave can, in turn, be used to change the position of magnetic domain walls by means of the spin-transfer torque effect generated from magnon spin current. This mutual interaction between spin waves and magnetic domain walls opens up the possibility of realizing all-magnon spintronic devices, in which one spin-wave signal can be used to control others by reconfiguring magnetic domain structures. 

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2. Atomic and Electronic Structure of Strongly Charged Domain Walls in van der Waals α-In ₂ Se ₃

   https://doi.org/10.1021/acs.nanolett.6c00418  

   Nolan, Gillian; Han, Edmund; Nahid, Shahriar Muhammad; Carmichael, Patrick; van_der_Zande, Arend M; Schleife, André; Huang, Pinshane Y (April 2026, Nano Letters)

   Here, we use atomic resolution scanning transmission electron microscopy (STEM) and first-principles calculations to study the atomic and electronic structure of strongly charged domain walls in α-In2Se3. STEM imaging and density functional theory (DFT) show that head-to-head (HH) domain walls contain a layer of β/β'-In2Se3, whereas tail-to-tail (TT) domain walls are atomically abrupt. We apply 4D STEM and multislice electron ptychography to map ferroelectric domains in 2D and 3D, showing that nearly 180° domain walls exhibit complex, curved 3D structures that differ from ideal 180° structures. First-principles simulations predict localized conducting states within an ∼1 nm thick layer at both HH and TT domain walls, such as a midgap state at the β layer of the HH domain wall. These properties make strongly charged domain walls in α-In2Se3 excellent candidates for realizing 2D electron or hole gases and domain wall engineering in van der Waals ferroelectrics. 

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3. Spin excitations and dynamics in 2D magnets: An overview of magnons and magnetic skyrmions

   https://doi.org/10.1016/j.pquantelec.2025.100564  

   Wu, Yingying; Balicas, Luis; Cheng, Ran; Zhang, Xiao-Xiao (April 2025, Progress in Quantum Electronics)

   van der Waals magnetic materials open up exciting possibilities to investigate fundamental spin properties in low-dimensional systems and to build compact functional spintronic structures. This review focuses on the recent progress in two-dimensional(2D) magnets that explore beyond the homogenous magnetically-ordered state, including magnons (spin waves), magnetic skyrmions, and complex magnetic domains. Properties of these spin and topology excitations in 2D magnets provide insights into spin-orbit interactions and other forms of coupling between electrons, phonons, and spin-dependent excitations. Such spin-based quasiparticles can also serve as information carriers for next-generation high-speed computing elements. We will first lay out the general theoretical basis of dynamical responses in magnetic systems, followed by detailed descriptions of experimental progress in magnons and spin textures (including magnetic domains and skyrmions). Discussion on the experimental techniques and future perspectives are also included. 

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4. Soliton walls paired by polar surface interactions in a ferroelectric nematic liquid crystal

   https://doi.org/10.1038/s41467-022-31593-w  

   Basnet, Bijaya; Rajabi, Mojtaba; Wang, Hao; Kumari, Priyanka; Thapa, Kamal; Paul, Sanjoy; Lavrentovich, Maxim O.; Lavrentovich, Oleg D. (December 2022, Nature Communications)

   Abstract Surface interactions are responsible for many properties of condensed matter, ranging from crystal faceting to the kinetics of phase transitions. Usually, these interactions are polar along the normal to the interface and apolar within the interface. Here we demonstrate that polar in-plane surface interactions of a ferroelectric nematic N F produce polar monodomains in micron-thin planar cells and stripes of an alternating electric polarization, separated by $${180}^{{{{{{\rm{o}}}}}}}$$ 180 o domain walls, in thicker slabs. The surface polarity binds together pairs of these walls, yielding a total polarization rotation by $${360}^{{{{{{\rm{o}}}}}}}$$ 360 o . The polar contribution to the total surface anchoring strength is on the order of 10%. The domain walls involve splay, bend, and twist of the polarization. The structure suggests that the splay elastic constant is larger than the bend modulus. The $${360}^{{{{{{\rm{o}}}}}}}$$ 360 o pairs resemble domain walls in cosmology models with biased vacuums and ferromagnets in an external magnetic field. 

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5. Magnons and magnetic fluctuations in atomically thin MnBi2Te4

   https://doi.org/10.1038/s41467-022-29996-w  

   Lujan, David; Choe, Jeongheon; Rodriguez-Vega, Martin; Ye, Zhipeng; Leonardo, Aritz; Nunley, T. Nathan; Chang, Liang-Juan; Lee, Shang-Fan; Yan, Jiaqiang; Fiete, Gregory A.; et al (December 2022, Nature Communications)

   Abstract Electron band topology is combined with intrinsic magnetic orders in MnBi 2 Te 4 , leading to novel quantum phases. Here we investigate collective spin excitations (i.e. magnons) and spin fluctuations in atomically thin MnBi 2 Te 4 flakes using Raman spectroscopy. In a two-septuple layer with non-trivial topology, magnon characteristics evolve as an external magnetic field tunes the ground state through three ordered phases: antiferromagnet, canted antiferromagnet, and ferromagnet. The Raman selection rules are determined by both the crystal symmetry and magnetic order while the magnon energy is determined by different interaction terms. Using non-interacting spin-wave theory, we extract the spin-wave gap at zero magnetic field, an anisotropy energy, and interlayer exchange in bilayers. We also find magnetic fluctuations increase with reduced thickness, which may contribute to a less robust magnetic order in single layers. 

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