Topological crystalline insulator states in the Ca${}_2$As family

Abstract

Topological crystalline insulators (TCI) are insulating electronic phases of matter with nontrivial topology originating from crystalline symmetries. Recent theoretical advances have provided powerful guidelines to search for TCIs in real materials. Using density functional theory, we identify a class of new TCI states in the tetragonal lattice of the Ca${}_2$As material family. On both top and side surfaces, we observe topological surface states protected independently by rotational and mirror symmetries. We show that a particular lattice distortion can single out the newly proposed topological protection by the rotational symmetry. As a result, the Dirac points of the topological surface states are moved to generic locations in momentum space away from any high symmetry lines. Such topological surface states have not been seen before. Moreover, the other family members, including Ca${}_2$Sb, Ca${}_2$Bi and Sr${}_2$Sb, feature different topological surface states due to their distinct topological invariants. We thus further propose topological phase transitions in the pseudo-binary systems such as (Ca${}_{1-x}$Sr${}_x$)${}_2$As and Ca${}_2$As${}_x$Sb${}_{1-x}$. Our work reveals rich and exotic TCI physics across the Ca${}_2$As family of materials, and suggests the feasibility of materials database search methods to discover new TCIs.

arXiv comment5 pages, 4 figures

References in corpus (34)

• Topological Insulators
• Topological insulators and superconductors
• Topological Insulators in Three Dimensions
• Topological Insulators with Inversion Symmetry
• Topological Crystalline Insulators
• Topological Materials: Weyl Semimetals
• Higher-Order Topological Insulators
• Topological quantum chemistry
• Colloquium: Topological Band Theory
• Topological Crystalline Insulators in the SnTe Material Class
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Experimental realization of a topological crystalline insulator in SnTe
• Topological crystalline insulator states in Pb(1-x)Sn(x)Se
• Symmetry-based Indicators of Band Topology in the 230 Space Groups
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• A topological crystalline insulator (TCI) phase via topological phase transition and crystalline mirror symmetry
• Topological classification of crystalline insulators through band structure combinatorics
• Hourglass Fermions
• Quantitative mappings between symmetry and topology in solids
• Observation of Dirac node formation and mass acquisition in a topological crystalline insulator
• Symmetry indicators and anomalous surface states of topological crystalline insulators
• Wannier Center Sheets in Topological Insulators
• Topology, Delocalization via Average Symmetry and the Symplectic Anderson Transition
• Topological Crystalline Kondo Insulator in Mixed Valence Ytterbium Borides
• Z2-topology in nonsymmorphic crystalline insulators: Mobius twist in surface states
• Topology of nonsymmorphic crystalline insulators and superconductors
• Evidence for massive bulk Dirac Fermions in Pb${}_{1-x}$Sn${}_x$Se from Nernst and thermopower experiments
• Wallpaper Fermions and the Nonsymmorphic Dirac Insulator
• Topological Crystalline Materials - General Formulation, Module Structure, and Wallpaper Groups -
• Robust spin-polarized midgap states at step edges of topological crystalline insulators
• Connecting higher-order topological insulators to lower-dimensional topological insulators
• Mapping the unconventional orbital texture in topological crystalline insulators
• A pressure-induced topological phase with large Berry curvature in Pb${}_{1-x}$Sn${}_x$Te
• Interfacial-state coupling induced topological phase transitions in SnTe (110) thin film

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• Glide Symmetry Protected Higher-Order Topological Insulators from Semimetals with butterfly-like Nodal Lines
• Nodal lines and mapping to mirror Chern numbers in Ca${}_2$As family
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• Electronic structure in a transition metal dipnictide TaAs2
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