Low-lying Electronic Structure of Rare-Earth Based Topological Nodal Line Semimetal Candidate DySbTe

Abstract

Lanthanide (Ln) based LnSbTe materials have garnered significant attention due to rich interplay of long range magnetic ordering and topological properties, driven by unique crystalline symmetry, 4f electron interactions, and pronounced spin-orbit coupling (SOC) effects. DySbTe, as a heavier lanthanide-based member of the LnSbTe family, stands out with its SOC and larger on site interactions on its 4f electrons, which arise due to the heavier Dy element. Here, we present a comprehensive study on the low-temperature bulk physical properties and the electronic structure of DySbTe using magnetic susceptibility, heat capacity, and electrical resistivity measurements, along with high-resolution angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy and spectroscopy (STM/S), and density functional theory calculations. Our thermodynamic measurements revealed an antiferromagnetic ordering below TN = 7.45 K and a subsequent magnetic phase transition at TN1 = 7.15 K. Our transport studies indicate a semimetallic behavior with unusual feature in the ordered state. Our ARPES measurements revealed a diamond-shaped Fermi pocket centered at the G point, with band features that evolve distinctly across various binding energies. STM/S results indicate a minimum in the density of states at around 100 meV below the Fermi level, and ARPES measurements reveal a significant gap present around the X point, differentiating DySbTe from other LnSbTe compounds. These findings enhance our understanding of the SOC effects on the electronic structure and topological properties in the LnSbTe family, highlighting DySbTe as a promising candidate for exploring the interplay between topology and magnetism.

Figures (5)

• Figure 1: Crystalline, electronic structures, and bulk properties of single-crystalline DySbTe. (a) Crystallographic unit cell. (b) Bulk Brillouin zone with the projected surface Brillouin zone marked with high symmetry points. Calculated bulk band structures along high symmetry directions (c) without and with (d) SOC taken into consideration. Temperature dependencies of (e) the inverse magnetic susceptibility, (f) the specific heat, and (g) the electrical resistivity measured with the magnetic field and electric current directions specified in the panels. The insets of panels (e,f) present the low-temperature data of (e) the magnetic susceptibility measured in zero-field-cooled (filled symbols) and field-cooled (open symbols) regimes, (f) the specific heat, and (g) the electrical resistivity. The red straight line in panel (e) marks the Curie-Weiss behavior described in the text. The horizontal dashed line in panel (f) represents the Dulong-Petit limit
• Figure 2: STM topography and STS spectra of DySbTe. (a) STM topography taken at setpoint conditions $(V_{bias}, I_{set})=(0.3~\text{V}, 150~\text{pA})$. In addition to the atomic lattice, dark and bright atomic defects are marked by the red and yellow arrows, respectively. The scale bar is 2 nm. The inset shows an FFT of the topograph. Bright is high and dark is low intensity, and the scale bar is 2 nm$^{-1}$. (b) STS spectra taken on the pristine lattice, as well as on the bright and dark defects.
• Figure 3: Plots of the Fermi map and constant energy contours in DySbTe. (a) ARPES measured Fermi surface (first leftmost panel ) and constant energy contours with various binding energies as noted on the top of each plot. (b) Theoretically obtained respective FS and energy contours. Experimental data was collected at SSRL endstation 5-2 at a temperature of $15$ K.
• Figure 4: Band structure of DySbTe along the $\overline{\text{M}}-\overline{\text{X}}-\overline{\text{M}}$ and $\overline{\text{M}}-\overline{\Gamma}-\overline{\text{M}}$. (a) ARPES measured band dispersion along the $\overline{\text{M}}-\overline{\text{X}}-\overline{\text{M}}$ direction with a measured photon energy of 75 eV. (b) Second derivative plot of (a). (c) Calculated surface electronic structure along $\overline{\text{M}}-\overline{\text{X}}-\overline{\text{M}}$ direction. (d) ARPES measured band dispersion along the $\overline{\text{M}}-\overline{\Gamma}-\overline{\text{M}}$ direction with a measured photon energy of 75 eV. (e) Second derivative plot of (d). (f) Calculated surface electronic structure along $\overline{\text{M}}-\overline{\Gamma}-\overline{\text{M}}$ direction. Experimental data was collected at SSRL endstation 5-2 at a temperature of 15K.
• Figure 5: Band structure of DySbTe along the $\overline{\text{X}}$-$\overline{\Gamma}$-$\overline{\text{X}}$. (a) ARPES measured band dispersion along the $\overline{\text{X}}-\overline{\Gamma}-\overline{\text{X}}$ direction with a measured photon energy of 75 eV. (b) Second derivative plot of (a). (c) ARPES measured band dispersion along the $\overline{\text{X}}-\overline{\Gamma}-\overline{\text{X}}$ with a different photon energy noted on top of the plot. (d) Calculated surface electronic structure along $\overline{\text{X}}-\overline{\Gamma}-\overline{\text{X}}$ direction. Experimental data was collected at SSRL endstation 5-2 at a temperature of $15$ K.