Plasmon modes in triple-point semimetal, its quadratic cousin, and Hopf semimetal

Ipsita Mandal

Home/Archive/arXiv

arXiv · 2610.18629

Plasmon modes in triple-point semimetal, its quadratic cousin, and Hopf semimetal

Ipsita Mandal

View original source ↗Read source document ↗Export metadata ↓

Abstract

We study collective charge excitations in pseudospin-1 triple-point semimetals within the random-phase approximation, considering both the linearised model with a flat-band and its quadratic-corrected counterpart. We analyse their density response, Drude weights, screening, plasmon dispersion and damping, particle-hole continua, and Friedel oscillations from the long-wavelength to the arbitrary-momentum regime. The quadratic correction renders the flat-band dispersive and endows it with a Fermi surface, thereby affecting the overall response. Comparisons with Weyl and Hopf semimetals reveal how bandstructure and quantum geometry jointly govern collective charge dynamics. While the Drude weights are determined by the Fermi surface and band-velocities, interband screening, plasmon dispersion, and Friedel oscillations reflect the quantum geometry of the eigenstates.

Explore related subjects

cond-mat.mes-hall hep-th

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Ipsita Mandal. 2026-10-13. Plasmon modes in triple-point semimetal, its quadratic cousin, and Hopf semimetal. https://arxiv.org/abs/2610.18629

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Fingerprints of an Imbert-Fedorov-like effect in the tunneling transmission of Rarita-Schwinger semi-metals

We study tunneling through a square barrier in a rotationally symmetric Rarita-Schwinger semi-metal and identify fingerprints of an Imbert-Fedorov-like effect in the tunneling transmission. The problem is intrinsically multichannel at all energies because there exist two propagating sectors with spin projections $m=1/2$ and $m=3/2$. We derive the transmission amplitudes analytically and compare the single-channel and coherent mixed-incidence cases in the two channels. Interestingly, we observe that tunneling at high energy shows a bias towards scattering into spin projection $3/2$ contributions. For single-channel injection, we find that the transmission remains symmetric under a mirror transformation of the incident angle. In contrast, for the coherent superposition, we find a directional asymmetry in the transmission probability $T(k_y)\neq T(-k_y)$. Importantly, this effect does not originate from an anisotropy of the dispersion. Instead, it arises from the phase structure of the multicomponent scattering states. The two spin projection sectors exhibit different scattering and barrier-propagation phases, which enter as interference terms when both channels appear as a coherent superposition. This interference term is identified as the cause of the broken mirror symmetry. We therefore discover an analog of the Imbert-Fedorov effect, at the level of interface-induced phase differences between internal wave components. Our result demonstrates that asymmetric tunneling can already occur in transport experiments, even in an idealized, isotropic multiband system, and should therefore not be automatically attributed solely to explicit band anisotropy.

cond-mat.mes-hall↗

arXiv2026

Room-Temperature Nonlinear Hall Effect in Polycrystalline Magnetic Multilayers

We report a zero-field nonlinear Hall effect in sputtered polycrystalline Ta/Pt/[Pt/Co/Fe/Ir]$_5$/Pt multilayers from 2 to 300 K. Angle-resolved transport reveals macroscopic in-plane anisotropy and a second-order response. The transverse voltage scales quadratically with current and remains unchanged across magnetization reversal. Conductivity scaling reveals strong scattering contributions, and first-principles calculations yield a symmetry-allowed Berry curvature dipole. Our findings support a mixed intrinsic-extrinsic response and establish a scalable platform for nonlinear electronics

cond-mat.mes-hall↗

arXiv2026

Phonons under confinement: Coarse-grained $U(1)$ charge and a new transport mechanism

An important feature of solid-state or cold atom systems in low dimensions is the restricted oscillations of ionic/atomic degrees of freedom in the confining directions, for which the conventional phonon from canonical quantization is not an ideal description. In this work we propose a general recipe to introduce this feature to otherwise unrestricted systems by mapping displacement fields to spin degrees of freedom, dubbed soft-corization. In the strong-confinement limit $S=1/2$, we demonstrate the validity of the approach with a harmonic chain; the results lead to a gapped fermionic model showing the absence of acoustic modes as a signature of the confinement of the entire chain. Despite the non-conserved total particle number in the presence of nearest-neighbor parings, the model holds a coarse-grained $U(1)$ symmetry with conserved polarization charge in the absence of nearest-neighbor hopping. This enables a new transport mechanism via "dimer-tumbling" instead of single-particle hopping. We then introduce a short-range interaction via anharmonicity; for energy scales slightly above the gap, it leads to a (quantum) phase transition to a nonreciprocal state carrying polarization charge current and heat current with spontaneous time reversal symmetry breaking (TRSB) of the type $\hat{T}^2=+1$. The non-reciprocity can be probed by measuring the change of inductance due to gauge fields in and out of the ordered phase.

cond-mat.mes-hall↗