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1. Dilute magnetic impurity-induced effective phonon magnetic moment in Fe-doped monolayer MoS ₂

   https://doi.org/10.1088/2053-1583/ae04fc  

   Mustafa, Hussam; Ye, Gaihua; Nnokwe, Cynthia; Fang, Mengqi; Kandil, Mohamed; Al-Mahboob, Abdullah; Wu, Kai; Stollenwerk, Andrew James; Kidd, Timothy E; Shand, Paul M; et al (September 2025, 2D Materials)

   Abstract Realization of large effective phonon magnetic moment in monolayer MoS₂has established an important route for exploring intriguing magnetic phenomena in a nonmagnetic material. The sizable coupling between the orbital transition and the circularly polarized phonon results in the large effective phonon magnetic moment. In this work, using magneto-Raman spectroscopy, we investigate substitutional doping of magnetic atoms as a tuning knob of the electronic and phononic properties of MoS₂. We show that Fe-doping polarizes the spin of the conduction bands and introduces a localized Fe band underneath the conduction band. As a result, an additional orbital transition between the Mo 4dand Fe 3dstates emerges, producing an orbital-phonon hybridized mode at 283 cm⁻¹. Our magnetic field dependent measurements demonstrate that this new mode carries 2.8 ${\mu }_{\mathrm{B}}$effective phonon magnetic moment, which is comparable to that of the undoped MoS₂. Moreover, even though a long-range magnetic order is absent in Fe-doped MoS₂, the local magnetic moment of Fe modifies the nature of the spin fluctuation, producing monotonically increasing quasielastic scattering spectral weight as temperature decreases. Our results highlight two-dimensional dilute magnetic semiconductors synthesized by substitutional doping as a promising material platform to manipulate the phonon magnetic moment through orbital-phonon coupling. 

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2. Lattice-Charge Coupling in a Trilayer Nickelate with Intertwined Density Wave Order

   https://doi.org/10.1103/s5j9-cbg7  

   Jia, Xun; Shen, Yao; LaBollita, Harrison; Chen, Xinglong; Zhang, Junjie; Li, Yu; Zhao, Hengdi; Kanatzidis, Mercouri G; Krogstad, Matthew; Zheng, Hong; et al (January 2026, Physical Review X)

   Intertwined charge and spin correlations are ubiquitous in a wide range of transition metal oxides and are often perceived as intimately related to unconventional superconductivity. Theoretically envisioned as driven by strong electronic correlations, the intertwined order is usually found to be strongly coupled to the lattice as signaled by pronounced phonon softening. Recently, both charge and spin density waves (CDW and SDW) and superconductivity have been discovered in several Ruddlesden-Popper (RP) nickelates, in particular trilayer nickelates $R{E}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$( $RE=\mathrm{Pr}$, La). The nature of the intertwined order and the role of lattice-charge coupling are at the heart of the debate about these materials. Using inelastic x-ray scattering, we mapped the low-energy phonon dispersions in $R{E}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$and found no evidence of softening near the CDW wave vector over a wide temperature range, which contrasts with the pronounced anomalies frequently observed in cuprate superconductors. Calculations of the electronic susceptibility revealed a peak at the observed SDW ordering vector but not at the CDW wave vector. Our experimental and theoretical findings highlight the crucial role of the spin degree of freedom and establish a foundation for understanding the interplay between superconductivity and density-wave transitions in RP nickelate superconductors and beyond. 

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3. Dilute Magnetic Impurity-Induced Effective Phonon Magnetic Moment in Fe-doped Monolayer MoS$$_2$$

   https://doi.org/10.5281/zenodo.16867938  

   JIN, WENCAN; He, Rui (January 2025, Zenodo)

   Realization of large effective phonon magnetic moment in monolayer MoS$$_2$$ has established an important route for exploring intriguing magnetic phenomena in a nonmagnetic material. The sizable coupling between the orbital transition and the circularly polarized phonon results in the large effective phonon magnetic moment. In this work, using magneto-Raman spectroscopy, we investigate substitutional doping of magnetic atoms as a tuning knob of the electronic and phononic properties of MoS$$_2$$. We show that Fe-doping polarizes the spin of the conduction bands and introduces a localized Fe band underneath the conduction band. As a result, an additional orbital transition between the Mo 4$$d$$ and Fe 3$$d$$ states emerges, producing an orbital-phonon hybridized mode at 283 cm$$^{-1}$$. Our magnetic field dependent measurements demonstrate that this new mode carries 2.8 $$\mu_B$$ effective phonon magnetic moment, which is comparable to that of the undoped MoS$$_2$$. Moreover, even though a long-range magnetic order is absent in Fe-doped MoS$$_2$$, the local magnetic moment of Fe modifies the nature of the spin fluctuation, producing monotonically increasing quasielastic scattering spectral weight as temperature decreases. Our results highlight two-dimensional dilute magnetic semiconductors synthesized by substitutional doping as a promising material platform to manipulate the phonon magnetic moment through orbital-phonon coupling. 

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4. Electron-phonon coupling of the iron pnictide superconductor Ba(Fe0.92Co0.08)2As2

   https://doi.org/10.1364/LS.2023.LW5F.3  

   Bartenev, Alexander; Kolodka, Roman S; Eom, Ki-Tae; Kang, Jong-Hoon; Rua, Adrian; Theran, Larry; Verbel, Camilo; Hellstrom, Eric E; Eom, Chang-Beom; Rua, Armando; et al (October 2023, Optica Publishing Group)

   Femtosecond photoexcitation of Ba(Fe_0.92Co_0.08)₂As₂superconductors reveals distinct dynamics of laser fluence-dependent ultrafast processes. The modified two-temperature model shows the complex interplay between thermalization time constants, electron-phonon coupling parameters, and level of optical excitation. 

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5. Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles

   https://doi.org/10.1002/smll.202402940  

   Nguyen, Minh Dang; Deng, Liangzi; Lee, Jong Moon; Resendez, Karla M; Fuller, Maggie; Hoijang, Supawitch; Robles‐Hernandez, Francisco; Chu, Ching‐Wu; Litvinov, Dmitri; Hadjiev, Viktor G; et al (July 2024, Small)

   Abstract Iron oxide nanoparticles (IONPs) are widely used for biomedical applications due to their unique magnetic properties and biocompatibility. However, the controlled synthesis of IONPs with tunable particle sizes and crystallite/grain sizes to achieve desired magnetic functionalities across single‐domain and multi‐domain size ranges remains an important challenge. Here, a facile synthetic method is used to produce iron oxide nanospheres (IONSs) with controllable size and crystallinity for magnetic tunability. First, highly crystalline Fe₃O₄IONSs (crystallite sizes above 24 nm) having an average diameter of 50 to 400 nm are synthesized with enhanced ferrimagnetic properties. The magnetic properties of these highly crystalline IONSs are comparable to those of their nanocube counterparts, which typically possess superior magnetic properties. Second, the crystallite size can be widely tuned from 37 to 10 nm while maintaining the overall particle diameter, thereby allowing precise manipulation from the ferrimagnetic to the superparamagnetic state. In addition, demonstrations of reaction scale‐up and the proposed growth mechanism of the IONSs are presented. This study highlights the pivotal role of crystal size in controlling the magnetic properties of IONSs and offers a viable means to produce IONSs with magnetic properties desirable for wider applications in sensors, electronics, energy, environmental remediation, and biomedicine. 

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