Electrons in helical magnetic field: a new class of topological metals

Abstract

Two theorems on electron states in helimagnets are proved. They reveal a Kramers-like degeneracy in helical magnetic field. Since a commensurate helical magnetic system is transitionally invariant with two multiple periods (ordinary translations and generalized ones with rotations), the band structure turns out to be topologically nontrivial. Together with the degeneracy, this gives an unusual spin structure of electron bands. A 2D model of nearly free electrons is proposed to describe conductive hexagonal palladium layers under an effective field of magnetically ordered CrO${}_2$ spacers in PdCrO${}_2$. The spin texture of the Fermi surface leads to abnormal conductivity.

References in corpus (8)

• Progress and prospects in magnetic topological materials
• Spin-group symmetry in magnetic materials with negligible spin-orbit coupling
• The properties of ultrapure delafossite metals
• Unconventional Anomalous Hall Effect in the Metallic Triangular-Lattice Magnet PdCrO2
• Unconventional aspects of electronic transport in delafossite oxides
• Topological spiral magnetism in the Weyl semimetal SmAlSi
• Magnetic structure of the conductive triangular-lattice antiferromagnet PdCrO2
• Kramers degeneracy in a magnetic field and Zeeman spin-orbit coupling in antiferromagnets

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• Minimal Models and Transport Properties of Unconventional $p$-Wave Magnets
• Superconducting phenomena in systems with unconventional magnets
• Impurity-induced Friedel oscillations in altermagnets and $p$-wave magnets
• Coexistence of $p$-wave magnetism and superconductivity
• Purely electrical detection of the spin-splitting vector in $p$-wave magnets based on linear and nonlinear conductivities
• The fate of $p$-wave spin polarization in helimagnets with Rashba spin-orbit coupling
• Higher-order bulk photovoltaic effects, quantum geometry and application to $p$-wave magnets
• EuAuSb: An odd-parity helical variation on altermagnetism
• Time reversal reserved spin valve and spin transistor based on unconventional $p$-wave magnets
• Topological bands in metals