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Tunable topological phase in 2D ScV$_6$Sn$_6$ kagome material

Chidiebere I. Nwaogbo, Sanjib K. Das, Chinedu E. Ekuma

TL;DR

The study demonstrates that a two-dimensional magnetic kagome material, $ScV_6Sn_6$, hosts Weyl-like crossings near the Fermi energy with a nonzero Chern number, enabling a large intrinsic anomalous Hall response. Using DFT with SOC, Wannier-function modeling, and edge-state analysis, it shows $|C|=1$ and an intrinsic AHC of about $257~Ω^{-1} cm^{-1}$ at the Fermi level. An external perpendicular electric field of about $0.40$ eV/Å drives a topological phase transition from a Weyl semimetal to a trivial metal, with edge states disappearing and Fermi pockets forming. The combination of ferromagnetism ($T_c≈89$ K), sizable MAE, and electric-field tunability makes 2D $ScV_6Sn_6$ a promising platform for tunable topological electronics and spintronics in 2D kagome systems.

Abstract

We investigate the topological properties of the vanadium-based 2D kagome metal ScV$_6$Sn$_6$, a ferromagnetic material with a magnetic moment of 0.86 $μ_B$ per atom. Using ab initio methods, we explore spin-orbit coupling-induced gapped states and identify multiple Weyl-like crossings around the Fermi energy, confirming a Chern number $|C| = 1$ and a large anomalous Hall effect (AHE) of 257 $Ω^{-1}$cm$^{-1}$. Our calculations reveal a transition from a topological semimetal to a trivial metallic phase at an electric field strength of $\approx$0.40 eV/Å. These findings position 2D ScV$_6$Sn$_6$ as a promising candidate for applications in modern electronic devices, with its tunable topological phases offering the potential for future innovations in quantum computing and material design.

Tunable topological phase in 2D ScV$_6$Sn$_6$ kagome material

TL;DR

The study demonstrates that a two-dimensional magnetic kagome material, , hosts Weyl-like crossings near the Fermi energy with a nonzero Chern number, enabling a large intrinsic anomalous Hall response. Using DFT with SOC, Wannier-function modeling, and edge-state analysis, it shows and an intrinsic AHC of about at the Fermi level. An external perpendicular electric field of about eV/Å drives a topological phase transition from a Weyl semimetal to a trivial metal, with edge states disappearing and Fermi pockets forming. The combination of ferromagnetism ( K), sizable MAE, and electric-field tunability makes 2D a promising platform for tunable topological electronics and spintronics in 2D kagome systems.

Abstract

We investigate the topological properties of the vanadium-based 2D kagome metal ScVSn, a ferromagnetic material with a magnetic moment of 0.86 per atom. Using ab initio methods, we explore spin-orbit coupling-induced gapped states and identify multiple Weyl-like crossings around the Fermi energy, confirming a Chern number and a large anomalous Hall effect (AHE) of 257 cm. Our calculations reveal a transition from a topological semimetal to a trivial metallic phase at an electric field strength of 0.40 eV/Å. These findings position 2D ScVSn as a promising candidate for applications in modern electronic devices, with its tunable topological phases offering the potential for future innovations in quantum computing and material design.

Paper Structure

This paper contains 6 sections, 3 figures.

Table of Contents

  1. INTRODUCTION
  2. COMPUTATIONAL METHODS
  3. RESULTS AND DISCUSSION
  4. Conclusions
  5. Acknowledgments
  6. Data availability

Figures (3)

  • Figure 1: (a) Side and (b) top views of the crystal structure of 2D ScV$_6$Sn$_6$. (c) Electronic band structure with the spin-up states (black bubbles) and spin-down states (red triangles). (d) Projected density of states onto atomic orbitals. The blue, red, and green lines represent the contributions from Sn, V, and Sc atoms, respectively, while the gray shading denotes the total density of states for the 2D structure. The left panel of (d) shows spin-up states, and the right panel shows spin-down states. The horizontal dotted line indicates the Fermi energy at $\approx0.40\,$ eV.
  • Figure 2: (a) Spin–orbit-coupling (SOC)–resolved electronic band structure of the 2D ScV$_6$Sn$_6$ slab, showing momentum-resolved orbital contributions. (b) Edge state dispersion along the [110] edge, with red regions indicating higher spectral weight and blue indicating lower weight. (c) Intrinsic anomalous Hall conductivity (AHC), $\sigma_{xy}$ (in $\Omega^{-1}~\text{cm}^{-1}$), as a function of energy. The horizontal dashed lines in (a) and (b), and the vertical dashed line in (c), indicate the Fermi energy at $\approx 0.42\,$eV. The horizontal dashed line in (c) marks the corresponding value of $\sigma_{xy} \sim 257\,\Omega^{-1}~\text{cm}^{-1}$ at the Fermi energy.
  • Figure 3: (a) Topologically protected edge state in the TSM phase. The white dashed lines in the inset highlight the closing of the topological gap in the surface at 'w'. (b) Berry curvature distributions of FM 2D ScV$_6$Sn$_6$ in the first Brillouin zone, with red regions marking Berry curvature singularities. (c)-(d) Fermi surface of the 110 slab: (c) without external fields and (d) with an electric field of 0.4 eV/Å, highlighting changes in Fermi pockets at the critical E-field. (e) The topological phase transition from the TSM phase ($|C|=1$) to the trivial phase ($|C|=0$), with the white dashed line showing the transition regime. (f) Edge states of FM 2D ScV$_6$Sn$_6$ (110) at a critical E-field of 0.4 eV/Å, where red lines enclose bands containing nodal points. The dashed green box represents the position of the Weyl point $w$, while the dotted black line indicates the Fermi level.