Browsing by Author "Suneetha, N."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Anticipation of Large Intrinsic Spin Hall Conductivity in Mercury Chalcogenides: A First-Principles Study
    (John Wiley and Sons Inc, 2024) Suneetha, N.; Ananthram, K.S.; Tarafder, K.
    The report carried out detailed first-principle calculations of Mercury chalcogenides (HgX; X = Te, Se and S) using density functional theory, verifying the bulk band inversion property with different exchange-correlation functionals. The Wannier function method is used to study the non-trivial topology of HgX systems, spin Berry curvature, and intrinsic spin Hall conductivity. Quantized intrinsic spin Hall conductivity is observed in the HgX systems. Large intrinsic spin Hall conductivity is found in the systems due to a strong spin Berry curvature accumulation near the triply degenerate points in the Brillouin zone. Calculation shows that the intrinsic spin Hall conductivity for all three HgX systems has stable plateaus, with Mercury Telluride having a maximum width of up to 1.05 eV. The maximum intrinsic spin Hall conductivity of –931 (Formula presented.) /e ((Formula presented.)) is obtained in mercury sulfide, higher than the reported values for spin Hall conductivity and the plateau width in typical topological insulators such as (Formula presented.), (Formula presented.), and (Formula presented.) as well as in transition metal pnictides (TaX, X = As, P and N) and transition metal iridates. © 2024 Wiley-VCH GmbH.
  • No Thumbnail Available
    Item
    First Principles Studies of Topological Insulating Behavior in Lanthanum-Monopnictides and their Heterostructures
    (John Wiley and Sons Inc, 2024) Ananthram, K.S.; Suneetha, N.; Tarafder, K.
    The topological insulating behavior of LaX (X = Bi, Sb, As, and P) and their heterostructure combinations are investigated. The system's bulk-band-inversion is analyzed, and the (Formula presented.) -topological indexes are calculated using LDA and mBJLDA exchange functionals. Strong topological insulating behavior in LaBi is confirmed from bulk band inversion. Linearly dispersive Dirac-cone in the (001)-surface band structure is observed. The other LaX binaries also exhibit bulk-band-inversion under LDA+SOC settings but disappear after including the mBJ potential. The robustness of the surface Dirac cone is tested by estimating the surface band structure under uniaxial strain. The result shows that Dirac-cone in the (001)-surface is unaltered only for the LaBi system and destroyed in all other three binaries, concluding the topologically trivial nature of LaP, LaSb, and LaAs. The investigation is further extended to study the multilayer LaX1/LaX2 systems composed of an alternate stacking of two different LaX binaries. The findings suggest that the multilayer structures exhibit topological insulating behavior only when LaBi is present in the system. Bulk-band-inversion and surface Dirac-cone structures in LaBi/LaAs, LaBi/LaSb, and LaBi/LaP multilayers are observed. Furthermore, the surface Dirac cones remain unchanged under the influence of TR-preserving perturbation, confirming these systems possess strong topological insulating character. © 2023 Wiley-VCH GmbH.