Fermi liquid theory of $d$-wave altermagnets: demon modes and Fano-demon states

Abstract

We develop a Fermi liquid theory of $d$-wave altermagnets and apply it to describe their collective excitation spectrum. We predict that in addition to a conventional undamped plasmon mode, where both spin components oscillate in phase, there is an acoustic plasmon (or {\em demon}) mode with out-of-phase spin dynamics. By analyzing the dynamical structure factor, we reveal a strong dependence of the demon's frequency and spectral weight both on the Landau parameters and on the direction of propagation. Notably, as a function of the propagation angle, we show that the acoustic mode evolves from a {\em hidden state}, which has zero spectral weight in the density excitation spectrum, to a weakly damped propagating demon mode and then (below a critical interaction parameter) to a {\em Fano-demon mixed state}, which is marked by a strong hybridization with particle-hole excitations and a corresponding asymmetric line shape in the structure factor. Our Letter paves the way for applications of altermagnetic materials in optospintronics by harnessing collective electron spin oscillations beyond traditional magnon spin waves.

published, 7 pages, 3 figures

References in corpus (25)

• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Multifunctional Antiferromagnetic Materials with Giant Piezomagnetism and Noncollinear Spin Current
• Broken Kramers' degeneracy in altermagnetic MnTe
• Giant and tunneling magnetoresistance effects from anisotropic and valley-dependent spin-momentum interactions in antiferromagnets
• Altermagnetism: Exploring New Frontiers in Magnetism and Spintronics
• Antiferromagnetism in RuO${}_2$ as $d$-wave Pomeranchuk instability
• Observation of plaid-like spin splitting in a noncoplanar antiferromagnet
• Large band-splitting in $g$-wave type altermagnet CrSb
• Discovery of a metallic room-temperature d-wave altermagnet KV2Se2O
• Landau Theory of Altermagnetism
• Three-dimensional mapping of the altermagnetic spin splitting in CrSb
• Twisted Magnetic Van der Waals Bilayers: An Ideal Platform for Altermagnetism
• Absence of altermagnetic spin splitting character in rutile oxide RuO${}_2$
• Two-dimensional altermagnets: Superconductivity in a minimal microscopic model
• Crystal-symmetry-paired spin-valley locking in a layered room-temperature antiferromagnet
• Observation of Spin Splitting in Room-Temperature Metallic Antiferromagnet CrSb
• Description of two-dimensional altermagnetism: Categorization using spin group theory
• Interplay of altermagnetism and weak ferromagnetism in two-dimensional RuF${}_4$
• Charged-phonon theory and Fano effect in the optical spectroscopy of bilayer graphene
• Coulomb Drag in Altermagnets
• Collective modes in interacting two-dimensional tomographic Fermi liquids
• Fragile Unconventional Magnetism in RuO${}_2$ by Proximity to Landau-Pomeranchuk Instability
• Analytic approach to transport in superconducting junctions with arbitrary carrier density
• Magnetic field suppression of tomographic electron transport
• Viscoelastic tensor and hydrodynamics of altermagnets