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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. Raman study of layered breathing kagome lattice semiconductor Nb ₃ Cl ₈

   https://doi.org/10.1088/2053-1583/acfa10  

   Jeff, Dylan A; Gonzalez, Favian; Harrison, Kamal; Zhao, Yuzhou; Fernando, Tharindu; Regmi, Sabin; Liu, Zhaoyu; Gutierrez, Humberto R; Neupane, Madhab; Yang, Jihui; et al (September 2023, 2D Materials)

   Abstract Niobium chloride (Nb₃Cl₈) is a layered two-dimensional semiconducting material with many exotic properties including a breathing kagome lattice, a topological flat band in its band structure, and a crystal structure that undergoes a structural and magnetic phase transition at temperatures below 90 K. Despite being a remarkable material with fascinating new physics, the understanding of its phonon properties is at its infancy. In this study, we investigate the phonon dynamics of Nb₃Cl₈in bulk and few layer flakes using polarized Raman spectroscopy and density-functional theory (DFT) analysis to determine the material’s vibrational modes, as well as their symmetrical representations and atomic displacements. We experimentally resolved 12 phonon modes, five of which areA_1gmodes while the remaining seven areE_gmodes, which is in strong agreement with our DFT calculation. Layer-dependent results suggest that the Raman peak positions are mostly insensitive to changes in layer thickness, while peak intensity and full width at half maximum are affected. Raman measurements as a function of excitation wavelength (473–785 nm) show a significant increase of the peak intensities when using a 473 nm excitation source, suggesting a near resonant condition. Temperature-dependent Raman experiments carried out above and below the transition temperature did not show any change in the symmetries of the phonon modes, suggesting that the structural phase transition is likely from the high temperatureP $\overline{\text{3}m}$1 phase to the low-temperatureR $\overline{3m}$phase. Magneto-Raman measurements carried out at 140 and 2 K between −2 and 2 T show that the Raman modes are not magnetically coupled. Overall, our study presented here significantly advances the fundamental understanding of layered Nb₃Cl₈material which can be further exploited for future applications. 

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3. Magnetic order in nanogranular iron germanium (Fe _0.53 Ge _0.47 ) films

   https://doi.org/10.1088/1361-648X/ad8c0a  

   Zielinski, Ruthi; Nguyen, Nhat; Herrington, Bryce; Tarkian, Amir; Taha, Omar; Chin, Wai Kiat; Mahmood, Ather; Chen, Xiaoqian; Klewe, Christoph; Shafer, Padraic; et al (November 2024, Journal of Physics: Condensed Matter)

   Abstract We study the effect of strain on the magnetic properties and magnetization configurations in nanogranular Fe_xGe ${}_{1-x}$films ( $x=0.53\pm 0.05$) with and without B20 FeGe nanocrystals surrounded by an amorphous structure. Relaxed films on amorphous silicon nitride membranes reveal a disordered skyrmion phase while films near and on top of a rigid substrate favor ferromagnetism and an anisotropic hybridization of Fedlevels and spin-polarized Gespband states. The weakly coupled topological states emerge at room temperature and become more abundant at cryogenic temperatures without showing indications of pinning at defects or confinement to individual grains. These results demonstrate the possibility to control magnetic exchange and topological magnetism by strain and inform magnetoelasticity-mediated voltage control of topological phases in amorphous quantum materials. 

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4. Magnetotransport properties of layered Fe ₃ GeTe ₂ crystals

   https://doi.org/10.1088/2515-7639/ae5345  

   Weerahennedige, Hiruni; Karki, Yog; Aljeailan, Huda; Weeraratna, Hansaka; Ronau, Zane; Zeltmann, Steven E; Muller, David A; Jasinski, Jacek B; Sumanasekera, Gamini (April 2026, Journal of Physics: Materials)

   Abstract Van der Waals layered magnetic materials have recently received significant attention for their ability to exhibit antiferromagnetic or ferromagnetic (FM) properties, even at the few-layer or monolayer scale. Among them, Fe₃GeTe₂is one of the most extensively studied systems, crystallizing in a hexagonal structure as an itinerant FM with a Curie temperature (T_C) of ∼220 K in bulk form and strong magnetic anisotropy. In this study, temperature and magnetic field dependence of the four-probe resistance ( $R_{xx}),$thermopower (TEP) (S), and Hall resistance ( $R_{xy}$) were investigated in thick Fe₃GeTe₂flakes with different thicknesses to understand electron and spin transport, as well as spin and magnetic states. $R_{xx}$decreased with decreasing temperature, confirming metallic behavior, consistent with the observed reduction in the magnitude of the negative TEP. Negative magnetoresistance (MR) with the magnetic field normal to the sample plane exhibited a quadratic field dependence belowT_C. An anomalous Hall effect was observed belowT_C, where $R_{xy}\left(B\right)$showed a linear field dependence at low fields and saturation at higher fields. The anomalous Hall resistance ( $R_{xy}^A$) followed a dependence of $\alpha R_{xx}+\beta R_{xx}^2$. A positive in-plane MR was observed when the current was perpendicular to the magnetic field, attributed to increased scattering from the enhanced Lorentz force and related orbital effects. Additionally, a hysteresis behavior was observed when cycling the in-plane magnetic field, likely due to the delay in domain alignment in response to the changing field. 

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5. Enhanced stability and bulk superconducting properties of Ag intercalated Bi _1.6 Pb _0.4 Sr ₂ Ca ₂ Cu ₃ O ${}_{10+\delta }$

   https://doi.org/10.1088/1361-6668/ae5690  

   Gonzalez_Arevalo, D; Do, Huu T; Mark, Alexander C; Rodriguez, David; Zangeneh, Danial; Klie, Robert F; Hemley, Russell J; Man, N K (April 2026, Superconductor Science and Technology)

   Abstract Cuprate high-temperature superconductors (HTSCs) have long stood a promising candidates for various applications due to their high critical temperature ( $T_{\mathrm{c}}$) at ambient pressure. Practical limitations such as low bulk critical current densities ( $J_{\mathrm{c}}^{\mathrm{B}}$), sample inhomogeneities and chemical instability, however, have hindered their applicability. Increasing ${\mathit{T}}_{\mathrm{c}}$, $J_{\mathrm{c}}^{\mathrm{B}}$and the upper critical fields as well as maintaining the chemical stability in cuprates are therefore major goals for these materials science. Here, we characterize the electronic and structural properties of an Ag intercalated ${\mathrm{Bi}}_{1.6}{\mathrm{Pb}}_{0.4}{\mathrm{Sr}}_2{\mathrm{Ca}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{10+\delta }$sample prepared using a novel growth technique. The sample demonstrates enhanced electrical properties that have remained nearly constant over 8 years, while the non-silver Bi-2223 exhibits much degradation in both high- $T_{\mathrm{c}}$fractional phase and superconducting properties. We correlate these bulk electronic properties with structural probes to determine the critical role of Ag in these samples. The enhanced properties of these Ag intercalated cuprates suggest novel synthesis pathways will be key in developing more practical superconductors for applications. 

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