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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Kramers nodal lines and Weyl fermions in SmAlSi

Kramers nodal lines (KNLs) have recently been proposed theoretically as a special type of Weyl line degeneracy connecting time-reversal invariant momenta. KNLs are robust to spin orbit coupling and are inherent to all non-centrosymmetric achiral crystal structures, leading to unusual spin, magneto-electric, and optical properties. However, their existence in in real quantum materials has not been experimentally established. Here we gather the experimental evidence pointing at the presence of KNLs in SmAlSi, a non-centrosymmetric metal that develops incommensurate spin density wave order at low temperature. Using angle-resolved photoemission spectroscopy, density functional theory calculations, and magneto-transport methods, we provide evidence suggesting the presence of KNLs, together with observing Weyl fermions under the broken inversion symmetry in the paramagnetic phase of SmAlSi. We discuss the nesting possibilities regarding the emergent magnetic orders in SmAlSi. Our results provide a solid basis of experimental observations for exploring correlated topology in SmAlSi.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Anomalous Hall effect emerging from field-induced Weyl nodes in SmAlSi

The intrinsic anomalous Hall effect (AHE) has been reported in numerous ferromagnetic Weyl semimetals. However, the AHE in the antiferromagnetic (AFM) or paramagnetic (PM) state of Weyl semimetals has rarely been observed experimentally. Different mechanisms have been proposed to account for the emergence of the AHE from different types of magnetic order. Here, in this Letter, we propose a new model that explains the observed AHE in both the AFM and PM states of the noncentrosymmetric Weyl semimetal SmAlSi. The newly proposed mechanism is based on magnetic-field-induced Weyl node evolution, which qualitatively explains the temperature dependence of the anomalous Hall conductivity, which displays unconventional power-law behavior in both the AFM and PM states of SmAlSi.

Gao, Yuxiang [Rice University, Houston, TX (United↗
DOE OSTI2020

Materials Data on SmAlSi by Materials Project

AlSiSm is hexagonal omega structure-derived structured and crystallizes in the tetragonal I4_1md space group. The structure is three-dimensional. Sm is bonded to six equivalent Al and six equivalent Si atoms to form a mixture of edge and face-sharing SmAl6Si6 cuboctahedra. There are two shorter (3.19 Å) and four longer (3.20 Å) Sm–Al bond lengths. There are four shorter (3.19 Å) and two longer (3.22 Å) Sm–Si bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a distorted trigonal planar geometry to six equivalent Sm and three equivalent Si atoms. There are one shorter (2.41 Å) and two longer (2.42 Å) Al–Si bond lengths. In the second Al site, Al is bonded in a distorted trigonal planar geometry to six equivalent Sm and three equivalent Si atoms. There are two shorter (3.19 Å) and four longer (3.20 Å) Al–Sm bond lengths. There are one shorter (2.41 Å) and two longer (2.42 Å) Al–Si bond lengths. Si is bonded in a distorted trigonal planar geometry to six equivalent Sm and three Al atoms.

36 MATERIALS SCIENCE↗