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Ternary Zintl arsenides Eu21Mn4As18, Eu21Zn4As18, and quaternary solid solution Eu21Mn4As15.4Sb2.6have been synthesized and structurally characterized using single‐crystal X‐ray diffraction. Eu21Mn4As18and Eu21Mn4As15.4Sb2.6are reported here for the first time, whereas new structural insights are presented for the previously known Eu21Zn4As18. All title compounds crystallize in the Sr21Mn4Sb18structure type (space groupC2/m) and exhibit pronounced positional disorder affecting both cationic and anionic sites. This includes disorder on Eu atoms and As2dimers, as well as splitM(M = Mn, Zn) sites within the anionic [M8As22]48−clusters. Despite the disorder, the Zintl concept remains applicable to the novel Eu21Mn4As18phase, and the charge‐balanced composition can be expressed as 2 × Eu21Mn4As18= [Eu2+]42{[Mn8As22]48‐}{[As2]4‐}3[As3‐]8. Electronic structure calculations performed on the disorder‐free model of Eu21Zn4As18predict a bandgap of ≈1.1 eV.
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High-entropy engineering of the crystal and electronic structures in a Dirac material
Abstract Dirac and Weyl semimetals are a central topic of contemporary condensed matter physics, and the discovery of new compounds with Dirac/Weyl electronic states is crucial to the advancement of topological materials and quantum technologies. Here we show a widely applicable strategy that uses high configuration entropy to engineer relativistic electronic states. We take theAMnSb2(A= Ba, Sr, Ca, Eu, and Yb) Dirac material family as an example and demonstrate that mixing of Ba, Sr, Ca, Eu and Yb at theAsite generates the compound (Ba0.38Sr0.14Ca0.16Eu0.16Yb0.16)MnSb2(denoted asA5MnSb2), giving access to a polar structure with a space group that is not present in any of the parent compounds.A5MnSb2is an entropy-stabilized phase that preserves its linear band dispersion despite considerable lattice disorder. Although bothA5MnSb2andAMnSb2have quasi-two-dimensional crystal structures, the two-dimensional Dirac states in the pristineAMnSb2evolve into a highly anisotropic quasi-three-dimensional Dirac state triggered by local structure distortions in the high-entropy phase, which is revealed by Shubnikov–de Haas oscillations measurements.
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- PAR ID:
- 10516754
- Publisher / Repository:
- npj nature publishing group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1038/s41467-024-47781-9
