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Disorder in quantum magnetic materials can mimic the behaviour of quantum spin liquids, however, quantifying disorder is challenging, often requiring magnetic fields large enough to fully polarize the system. Here, Kim, Rathi and coauthors show how the fine spectroscopic structure of magnetization plateaus can be used to quantify disorder in magnetic insulators.

Phonons are the collective excitations of the lattice of a material, and can, in the case of chiral phonons, carry angular momentum, allowing for strong coupling to the magnetic properties of the material. Here, Cui, Bostrom and co-authors observe chiral magnon polarons, the hybridized quasiparticles of chiral phonons and magnons, in the van der Waals antiferromagnet FePSe₃.

Field-driven insulator-to-metal transition and associated colossal magnetoresistance have been reported in the magnetic nodal-line semiconductor Mn₃Si₂Te₆. Gu et al. measure infrared response across magnetic ordering and the transition, revealing a weakly metallic state instead of a traditional metallic state.

Van Hove singularities (VHS) are believed to exist in one and two dimensions, but rarely found in three dimensions (3D). Here the authors report the discovery of 3D VHS in a topological magnet EuCd₂As₂ by magneto-infrared spectroscopy.

Trivalent lanthanides are typically described using an ionic picture that leads to localized magnetic moments. Here authors show that the “textbook” description of lanthanides fails for Pr⁴⁺ ions where the hierarchy of single-ion energy scales can be tailored to explore correlated phenomena in quantum materials.

Semiconductors with large Landé g-factors allow for both highly spin-polarized states, and precise control of the spin dynamics. Here, the authors make superlattices of two semiconductors, InSb, and InAsSb, and by tuning the conduction and valence band overlap, achieve a Landé g-factor of 104.

The manuscript reports on the experimental observation of a Lifshitz transition in a topological insulator HfTe₅ subject to a strong magnetic field, which results in the formation of topological one-dimensional Weyl modes in the bulk of a three-dimensional material.

For molecular magnets and qubits, coupling between vibrations and electronic spins has a strong influence on spin state lifetime. Here, Kragskow et al present direct measurements of the vibronic transitions in a molecular magnet, showing the critical role of an “envelope effect” in the spectra.

Unique electronmagnetic response of Weyl semimetals have only been reported in static field regime. Here, the authors report evidence of a dynamical chiral anomaly response realized by internal collective lattice deformation with an external static magnetic field in a Weyl semimetal NbAs.

Transition metal complexes that display slow magnetic relaxation show promise for information storage, but our mechanistic understanding of the magnetic relaxation of such compounds remains limited. Here, the authors spectroscopically and computationally characterize the strength of spin–phonon couplings, which play an important role in the relaxation process.

The band structure of solid state systems can exhibit linear like dispersions resembling the Dirac equation in high-energy physics; however, the crystal structure anisotropy typically associated with solid state systems can lead to deviations from the symmetry of the original equation. Here, using Landau level spectroscopy, the authors report experimental evidence for isotropic fermions in 3D crystal structure of LaAlSi.

The proximity coupling of topological insulators with magnetic materials can give rise to exotic phenomenon such as the quantum anomalous Hall effect. Here, the authors use magneto-optical Landau level spectroscopy to investigate Pb_1-xSn_xSe-EuSe heterostructures finding evidence of a quantum confinement induced energy gaps in the topological surface states, that overshadow the magnetic proximity effects.