Second-order topological insulator induced by compensated altermagnetism without bulk spin splitting

Abstract

We theoretically demonstrate a second-order topological insulating phase induced by compensated altermagnetism, while keeping the bulk gap unchanged, in a two-dimensional topological insulator film. By introducing a layer-resolved out-of-plane $d$-wave altermagnetic term with opposite signs on the top and bottom layers, the system preserves $\mathcal{P}\mathcal{T}$ symmetry and maintains spin degeneracy in the bulk bands, while simultaneously gapping the helical edge states and generating localized corner states. The resulting higher-order phase is characterized by nonzero mirror-graded winding numbers, and an effective edge theory shows that the corner states arise from Dirac mass domain walls. We further determine the phase boundaries analytically and construct the corresponding topological phase diagram, establishing a robust route to higher-order topology without bulk spin splitting.

References in corpus (56)

• Topological Insulators
• Topological insulators and superconductors
• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Quantized Electric Multipole Insulators
• Higher-Order Topological Insulators
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Reflection symmetric second-order topological insulators and superconductors
• Crystal Hall effect in Collinear Antiferromagnets
• Higher-Order Topology in Bismuth
• Demonstration of a quantized microwave quadrupole insulator with topologically protected corner states
• Quantization of fractional corner charge in $C_n$-symmetric higher-order topological crystalline insulators
• Massive Dirac fermions and spin physics in an ultrathin film of topological insulator
• Visualization of higher-order topological insulating phases in two-dimensional dielectric photonic crystals
• Giant momentum-dependent spin splitting in centrosymmetric low Z antiferromagnets
• Topological Phases in Two-Dimensional Materials: A Brief Review
• Direct observation of altermagnetic band splitting in CrSb thin films
• Spontaneous anomalous Hall effect arising from an unconventional compensated magnetic phase in a semiconductor
• Higher-order Topology of Axion Insulator EuIn${}_2$As${}_2$
• Antiferromagnetism in RuO${}_2$ as $d$-wave Pomeranchuk instability
• Two-dimensional second-order topological insulator in graphdiyne
• Higher-Order Topological Insulator in Twisted Bilayer Graphene
• Crystal Thermal Transport in Altermagnetic RuO2
• Higher-Order Topological Insulators in Quasicrystals
• Discovery of a metallic room-temperature d-wave altermagnet KV2Se2O
• Finite-momentum Cooper pairing in proximitized altermagnets
• Engineering Corner States from Two-Dimensional Topological Insulators
• Two-dimensional higher-order topology in monolayer graphdiyne
• Universal Approach to Magnetic Second-Order Topological Insulator
• Fractional disclination charge in two-dimensional $C_n-$symmetric topological crystalline insulators
• Twisted Magnetic Van der Waals Bilayers: An Ideal Platform for Altermagnetism
• Universal Scaling of Quantum Anomalous Hall Plateau Transition
• Creation and Manipulation of Higher-Order Topological States by Altermagnets
• Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi2Se3/YIG heterostructures
• Bilayer stacking A-type altermagnet: A general approach to generating two-dimensional altermagnetism
• Field-free Josephson diode effect in altermagnet/normal metal/altermagnet junctions
• Phononic real Chern insulator with protected corner modes in graphynes
• Altermagnetism in the layered intercalated transition metal dichalcogenide CoNb${}_4$Se${}_8$
• Changes of Magnetism in a Magnetic Insulator due to Proximity to a Topological Insulator
• Cornertronics in Two-Dimensional Second-Order Topological Insulators
• Engineering second-order topological insulators via coupling two first-order topological insulators
• Altermagnetic Proximity Effect
• Single-mode lasing based on PT-breaking of two-dimensional photonic higher-order topological insulator
• Tunneling Magnetoresistance Effect in Altermagnets
• Engineering topologically protected zero-dimensional interface end states in antiferromagnetic heterojunction graphene nanoflakes
• The General Principle behind Magnetization-induced Second-Order Topological Corner States in the Kane-Mele Model
• Interlayer Coupling Induced Topological Phase Transition to Higher Order
• Two-Dimensional Higher-Order Topological Metals
• (Anti-)Altermagnetism from Orbital Ordering in the Ruddlesden-Popper Chromates Sr${}_{n+1}$Cr${}_n$O${}_{3n+1}$
• Helical Fermi Arc in Altermagnetic Weyl Semimetal
• Discovery of a high-temperature antiferromagnetic state and transport signatures of exchange interactions in a Bi2Se3/EuSe heterostructure
• Tunable two-dimensional Dirac-Weyl semimetal phase induced by altermagnetism
• Majorana modes in helical altermagnet without net magnetism and spin-orbit coupling
• Quantum anomalous Hall effect with tunable Chern numbers induced by d-wave sublattice-staggered altermagnetism