Spin-orbit enabled unconventional Stoner magnetism

Abstract

The Stoner instability remains a cornerstone for understanding metallic ferromagnets. This instability captures the interplay of Coulomb repulsion, Pauli exclusion, and two-fold fermionic spin degeneracy. In materials with spin-orbit coupling, this fermionic spin is generalized to a two-fold degenerate pseudospin which is typically believed to have symmetry properties as spin. Here we identify a distinct symmetry of this pseudospin that forbids it to couple to a Zeeman field. This `spinless' property is required to exist in five non-symmorphic space groups and has non-trivial implications for superconductivity and magnetism. With Coulomb repulsion, Fermi surfaces composed primarily of this spinless pseudospin feature give rise to Stoner instabilities into magnetic states that are qualitatively different than ferromagnets. These spinless-pseudospin ferromagnets break time-reversal symmetry, have a vanishing magnetization, are non-collinear, and exhibit altermagnetic-like energy band spin-splittings. In superconductors, for all pairing symmetries and field orientations, this spinless pseudospin extinguishes paramagnetic limiting. We discuss applications to superconducting UCoGe and magnetic NiS${}_{2-x}$Se${}_x$.

References in corpus (20)

• Classification of topological insulators and superconductors in three spatial dimensions
• Antiferromagnetic spintronics
• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Discovery of topological Weyl fermion lines and drumhead surface states in a room temperature magnet
• Topological semi-metals with line nodes and drumhead surface states
• Classification of reflection symmetry protected topological semimetals and nodal superconductors
• Magnetic Topological Quantum Chemistry
• Review of U-based Ferromagnetic Superconductors: Comparison between UGe2, URhGe, and UCoGe
• Extremely Large and Anisotropic Upper Critical Field and the Ferromagnetic Instability in UCoGe
• Topological transition from nodal to nodeless Zeeman splitting in altermagnets
• Unusual upper critical field of the ferromagnetic superconductor UCoGe
• Minimal Models for Altermagnetism
• Spinless hourglass nodal-line semimetals
• Non-symmorphic symmetry and field-driven odd-parity pairing in CeRh${}_2$As${}_2$
• Emerging research landscape of altermagnetism
• Direct observation of the bandwidth control Mott transition in the NiS${}_{2-x}$Se${}_x$ multiband system
• Lifshitz Transitions in the Ferromagnetic Superconductor UCoGe
• Double Dirac Nodal Line Semimetal with Torus Surface State
• Superconductivity of anomalous pseudospin
• Ising superconductivity: a first-principles perspective

Cited by in corpus (5)

• Mirror Chern Bands and Weyl Nodal Loops in Altermagnets
• Magnetic-field-tuned randomness in inhomogeneous altermagnets
• Impact of strong electronic correlations on altermagnets: the case of NiS2
• Orbital altermagnetism on the kagome lattice and possible application to $A$V${}_3$Sb${}_5$
• Altermagnetism Induced Bogoliubov Fermi Surfaces Form Topological Superconductivity