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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Band structure and Fermi surface nesting in LaSb 2

Here we use high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) to investigate the electronic structure of the charge density wave (CDW) system LaSb 2 . This compound is among an interesting group of materials that manifests both a CDW transition and lower temperature superconductivity. We find the DFT calculations to be in good agreement with our ARPES data. The Fermi surface of LaSb 2 consists of two small hole pockets close to Γ and four larger pockets near the Brillouin zone boundary. The key features of the Fermi surface do not vary significantly with temperature. A saddle point is present at -0.19 eV below the Fermi level at Γ. Saddle points in the band structure have more pronounced effects on materials properties when they are located closer to the Fermi level, making doped LaSb 2 compounds a potential interesting subject of future research. Multiple peaks are present in the generalized, electronic susceptibility calculations, indicating the presence of three possible nesting vectors. We were not able to detect any signatures of the CDW transition at 355 K down to the lowest temperature of 7 K, pointing to the subtle nature of this transition. This is unusual, given that such a high transition temperature is expected to be associated with the presence of a large CDW gap. This is confirmed through investigation of the Fermi surface and through analysis of momentum distribution curves. It is possible that changes are subtle and occur below current sensitivity of our measurements.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on LaSb by Materials Project

LaSb is Tetraauricupride structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. La3+ is bonded in a body-centered cubic geometry to eight equivalent Sb3- atoms. All La–Sb bond lengths are 3.43 Å. Sb3- is bonded in a body-centered cubic geometry to eight equivalent La3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaSb by Materials Project

LaSb is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. La3+ is bonded to six equivalent Sb3- atoms to form a mixture of edge and corner-sharing LaSb6 octahedra. The corner-sharing octahedral tilt angles are 0°. All La–Sb bond lengths are 3.28 Å. Sb3- is bonded to six equivalent La3+ atoms to form a mixture of edge and corner-sharing SbLa6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2AgSb3 by Materials Project

(LaSb)2AgSb crystallizes in the tetragonal P4/mmm space group. The structure is zero-dimensional and consists of one antimony molecule, one silver molecule, and two LaSb clusters. In each LaSb cluster, La3+ is bonded in a single-bond geometry to one Sb+2.33- atom. The La–Sb bond length is 2.70 Å. Sb+2.33- is bonded in a single-bond geometry to one La3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Trivial to nontrivial topology transition in rare-earth pnictides with epitaxial strain

The combination of magnetotransport and topological properties has brought great attention to rare-earth monopnictides semimetals. For some of them, like LaSb, it is unclear whether they show nontrivial topology or not based on density functional theory calculations and angular resolved photoemission spectroscopy measurements. Here we use hybrid density functional theory to demonstrate that LaSb is in fact a trivial topological semimetal, in agreement with experiments, but on the verge of a transition to a topological phase. In this work, we show that under compressive epitaxial strain, the La $\textit{d}$ band crosses the Sb $\textit{p}$ band near the $\textit{Z}$ point in the Brillouin zone, stabilizing a topologically nontrivial phase, opening unique opportunities to probe the inter-relation between magnetotransport properties and the effects of band topology by examining epitaxially strained and unstrained thin films of the same material.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Extreme Transverse Magnetoresistance in TiZn 16

Extreme magnetoresistance (XMR) is a phenomenon characterized by an increase in resistance by factors of 10 4 –10 7 % when a magnetic field is applied. This phenomenon is found in a number of semimetals such as WTe 2 , PtSn 4 , Cd 3 As 2 , and LaSb. The origin of XMR is still hotly debated, possibly with different materials having different (or multiple) explanations. Extreme transverse magnetoresistance of up to 8000% at 14 T and 1.8 K is measured in TiZn 16 , a semimetal with a multitude of bands crossing the Fermi energy, akin to PtSn 4 . The magnetoresistance is suppressed when the magnetic field is rotated to be parallel to the applied current, similar to PtSn 4 and PdSn 4 . The resistance of TiZn 16 follows Kohler's rule, but displays different behavior under an applied transverse field and under a longitudinal magnetic field, suggesting distinct electrical phases. Also present are Shubnikov-de Haas and de Haas-van Alphen oscillations with a transverse magnetic field up to 43 T, showing that despite an insulator-like temperature-resistance curve, charge carriers are still present. This positions TiZn 16 as an interesting addition to the investigation of XMR materials as a multi-band metal with complex Fermi surface geometries.

extreme magnetoresistance↗
DOE OSTI2021

Synthesis and Transport Properties of the Family of Zintl Phases Ca 3 RESb 3 (RE = La–Nd, Sm, Gd–Tm, Lu): Exploring the Roles of Crystallographic Disorder and Core 4f Electrons for Enhancing Thermoelectric Performance

Zintl phases with complex crystal structures have been studied as promising candidate-materials for thermoelectric (TE) applications. Here, we report the syntheses of the family of rare-earth metal Zintl phases with the general formula Ca 4–x RE x Sb 3 (x ≈ 1; RE = La–Nd, Sm, Gd–Tm, Lu). The structural elucidation is based on refinements of single-crystal X-ray diffraction data for 12 unique chemical compositions. The cubic structure is confirmed as belonging to the anti-Th 3 P 4 structure type (space group I4¯3d, no. 220, Z = 4), where the Ca and RE atoms share the same atomic site with ca. 75% and 25% occupancies, respectively. Such crystallographic disordering of divalent Ca and trivalent RE atoms in the structure provides a pathway to intricate bonding. The latter, together with the presence of heavy elements such as Sb and the lanthanides, are expected to enhance the scattering probability of phonons, thereby leading to as low thermal conductivity κ as that of the ordered RE 4 Sb 3 . The drive of the hypothetical parent compound Ca 4 Sb 3 to be stabilized by alloying with rare-earth metals can be understood following the Zintl-Klemm concept, as the resultant formula may be rationalized as (Ca 2+ ) 3 RE 3+ (Sb 3– ) 3 , indicating the realization of closed-shell electronic configurations for all elements. This notion is confirmed by electronic structure calculations, which reveal narrow bandgaps E g = 0.77 and 0.53 eV for Ca 3 LaSb 3 and Ca 3 LuSb 3 , respectively. Additionally, the incorporation of RE atoms into the structure drives the phase into a state of a degenerate semiconductor with dominant hole charge carriers.

36 MATERIALS SCIENCE↗