Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2411.06088

Existence of dual topological phases in Sn-based ternary chalcogenides

Ramesh Kumar·Mukhtiyar Singh
View original source ↗Read source document ↗Export metadata ↓

Abstract

It is quite intriguing to investigate the transition from a topological insulator (TI) phase to topological crystalline insulator (TCI) phase in a material as the latter has an advantage over the former in controlled device applications. This work investigates the existence of this dual topological behavior in Sn-based ternary chalcogenides family PbSnX2 (X=S, Se, Te) under the hydrostatic pressure using first-principles approach. These materials are dynamically sTABLE at ambient and elevated pressure conditions up to which the topological phase transitions (TPTs) are studied. This family have a topologically trivial ground state with direct band gap values 0.338 eV, 0.183 eV and 0.217 eV for PbSnS2, PbSnSe2 and PbSnTe2, respectively. The first TPT i.e., TI phase for these materials is observed, under the effect of external pressure of 5 GPa, 2.5 GPa and 3.5 GPa, with a single band inversion at F-point in the bulk band structure and an odd number of Dirac cones along the (111) surface. A further increase in pressure to 5.5 GPa, 3 GPa and 4 GPa results in another band inversion at Γ-point and an even number of Dirac cones along the (111) plane. These even number of band inversions suggest that (\(\bar{1}2\bar{1}\)) surface has mirror symmetry around (\(\bar{1}0\bar{1}\)) plane and hence, the TCI phase is obtained. This TCI phase is further corroborated with even value of mirror Chern number calculated using winding of Wannier charge centers.

Explore related subjects

cond-mat.mtrl-scicond-mat.str-el

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ramesh Kumar, Mukhtiyar Singh. 2024-11-19. Existence of dual topological phases in Sn-based ternary chalcogenides. https://doi.org/10.1103/physrevb.111.195128

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Incommensurate structural and magnetic modulations in potassium-rich cryptomelane, K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$)

Cryptomelane is a hollandite-like material consisting of K$^+$ cations in an $α$-MnO$_2$ tunnel-like crystallographic motif. Cryptomelane with stoichiometry K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$) has been synthesized and its magnetic properties investigated using variable-temperature magnetic susceptibility, heat capacity, and neutron powder diffraction. Three distinct transitions at $T_1=184$\,K, $T_2=54.5$\,K, and $T_3=24$\,K are observed. At $T_1$ there is a subtle tetragonal$\rightarrow$monoclinic transition associated with emergence of a set of non-magnetic superstructure peaks indexable to a $\vec{k}_\mathrm{struc}\approx0.74\vec{c^*}$ incommensurate modulation parallel to the $α$-MnO$_2$ tunnels. Our findings are consistent with a relation previously reported in titanate hollandites, that $x\approx2|\vec{k}_\mathrm{struc}|$. Magnetic Bragg peaks emerge below $T_2=54.5$\,K, and their positions indicate an incommensurate modulated magnetic structure. The model consistent with the data is a dual-$\vec{k}_\mathrm{mag}$ structure with a ferromagnetic $|\vec{k}_\mathrm{mag}|=0$ component and an incommensurate $\vec{k}_\mathrm{mag}\approx0.37\vec{c^*}$, with the latter most likely to be helical. The period of oscillation of the incommensurate magnetic component is in line with predictions based on a Heisenberg spin Hamiltonian [Mandal \textit{et al}. Phys. Rev. B 90, 104420 (2014)]. Below $T_3=24$\,K, there is a magnetic transition, which gives rise to a different set of magnetic Bragg peaks indicative of a highly complex magnetic structure.

cond-mat.mtrl-sci↗
arXiv2026

An anisotropic functional for two-dimensional material systems

Density function theory is the workhorse of modern electronic structure theory. However, its accuracy in practical calculations is limited by the choice of the exchange-correlation potential. In this respect, two-dimensional materials pose a special challenge, as all these materials and their heterostructures have a crucial similarity. The underlying atomic structures are strongly spatially inhomogeneous, implying that current exchange-correlation functionals, that in almost all cases are isotropic, are ill-prepared for an accurate description. We present an anisotropic screened-exchange potential, that remedies this problem and reproduces the band-gap of 2D materials as well as the piecewise linearity of the total energy with fractional occupation number.

cond-mat.mtrl-sci↗
arXiv2026

Thermally-driven reorientation of the Néel vector in altermagnetic MnTe

Altermagnets are novel magnetic systems that possess a spin-polarized electronic band structure without a net magnetic moment, making them promising for device applications. Hexagonal MnTe, a prototypical altermagnet, arguably exhibits the most properties consistent with theoretical predictions, including an anomalous Hall effect despite a vanishing net magnetization, and altermagnetinduced electronic band splitting. However, fundamental questions remain, including why some effects only appear significantly below the magnetic ordering temperature. Here, we resolve this discrepancy by revealing a reorientation of the Néel vector in single-crystalline MnTe. The Néel vector points 30° from the a-axis at low $T$, before aligning directly with the a-axis around $T\simeq 260$ K. We attribute this to single-ion anisotropy, which depends on temperature-dependent lattice parameters. We obtained these results using muon-spin spectroscopy, magnetization measurements, and X-ray diffraction; we show that the findings are consistent with neutron diffraction. Manipulating this effect, for example through strain, could unlock sensitive electronic detection schemes for external stimuli, paving the way for functional altermagnetic devices.

cond-mat.mtrl-sci↗