@unpublished{que2026tunableflatbandsurface,

title = {Tunable flat band on the surface of a rhombohedral kagome ferromagnet},

author = {X. Que and Q. He and L. Zhou and L. Prodan and V. Tsurkan and I. Kézsmárki and H. Takagi and D. Huang},

url = {https://arxiv.org/abs/2609.19857},

doi = {10.48550/arXiv.2609.19857},

year  = {2026},

date = {2026-09-17},

urldate = {2026-09-01},

abstract = {A central goal in the exploration of kagome-based materials is the realization of a flat band that has meV bandwidth and lies close to the Fermi energy. The prevailing assumption is that band flattening originates from destructive hopping processes on the kagome lattice. We perform scanning tunneling microscopy (STM) on the layered kagome ferromagnet Fe3Sn2 and show that it indeed hosts a flat band near the Fermi energy, which is manifested as a sharp peak in the differential tunneling conductance. First-principles slab calculations reveal, however, that this band is flattened not by the destructive interference of intralayer hopping, but by interlayer hopping between rhombohedral-stacked kagome planes in Fe3Sn2, and is confined to the surface layer. This surface band, forming in the vicinity of the Brillouin zone corners K¯ and K′¯, exhibits rich magnetic-field dependence, including fine structure due to valley-symmetry breaking by rotated Fe moments, as well as a persistent diamagnetic shift associated with orbital magnetic moments, all reproduced by our calculations. Our results, highlighting the crucial role of layer stacking on the band structure of kagome magnets, demonstrate experimentally an alternative mechanism of generating magnetically tunable flat bands in atomically thin volumes of topological magnets.},

note = {arXiv.2609.19857},

keywords = {A3},

pubstate = {published},

tppubtype = {unpublished}

}

@unpublished{jarc2026ramansignaturesnonreciprocalmagnetic,

title = {Raman signatures of a non-reciprocal magnetic phase transition in Ca_{2}RuO_{4}},

author = {G. Jarc and G. Tartaglia and F. Gabriele and F. Forte and A. Guarino and A. Montanaro and E. M. Rigoni and N. Khatiwada and C. Lincetto and G. Bartolini and A. Mastropasqua and S. Y. Mathengattil and M. Malvestuto and M. Waqee-Ur-Rehman and R. Fittipaldi and J. Deisenhofer and A. A. Tsirlin and A. Vecchione and M. Cuoco and D. Fausti},

url = {https://arxiv.org/abs/2609.07565},

doi = {10.48550/arXiv.2609.07565},

year  = {2026},

date = {2026-09-07},

urldate = {2026-09-07},

abstract = {The magnetic behavior of Ca2RuO4 represents a unique puzzle due to the interplay of strong electronic correlations, magneto-elastic interactions, and large spin-orbit coupling. At low temperatures, an anomalous Mott insulating state emerges, characterized by a complex antiferromagnetic order with a collective amplitude excitation of the magnetic moment which has been discussed in analogy with the Higgs mode. We report here evidence of a magnetic first-order phase transition driven by an out-of-plane magnetic field along the crystallographic c-axis of Ca2RuO4. Raman measurements in magnetic field reveal the emergence of mode of magnetic origin and a concomitant modification of the coupling between a phonon and the Higgs amplitude mode. Both the Raman features are characterized by a non-reciprocal hysteresis in magnetic field. Surprisingly, the observed phase transition does not affect the Raman scattering from the in-plane magnons, indicating that the dipolar antiferromagnetic order is preserved. This is consistent with the onset of a new quadrupolar field-controlled state, whose fluctuations structure can trigger an hybridization between the lattice and the magnetic Higgs mode resulting in the observed Raman features.},

note = {arXiv.2609.07565},

keywords = {A1, C4},

pubstate = {published},

tppubtype = {unpublished}

}