Realization of Z₂ Topological Metal in Single-Crystalline Nickel Deficient NiV₂Se₄

Titelangaben

Ramakrishnan, Sitaram ; Matteppanavar, Shidaling ; Schönleber, Andreas ; Patra, Bikash ; Singh, Birender ; Thamizhavel, Arumugam ; Singh, Bahadur ; Ramakrishnan, Srinivasan ; van Smaalen, Sander:
Realization of Z₂ Topological Metal in Single-Crystalline Nickel Deficient NiV₂Se₄.
In: Annalen der Physik. Bd. 535 (2023) Heft 6 . - 2200611.
ISSN 1521-3889
DOI: https://doi.org/10.1002/andp.202200611

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Abstract

Abstract Temperature-dependent electronic and magnetic properties are reported for nickel-deficient NiV2Se4. Single-crystal X-ray diffraction shows it to crystallize in the monoclinic Cr3S4 structure type with space group I2/m and vacancies on the Ni site, resulting in the composition Ni0.85V2Se4 in agreement with our electron-probe microanalysis. Structural distortions are not observed down to 1.5 K. Nevertheless, the electrical resistivity shows metallic behavior with a broad anomaly around 150–200 K that is also observed in the heat capacity data. This anomaly indicates a change of state of the material below 150 K. It is believed that this anomaly could be due to spin fluctuations or charge-density-wave fluctuations, where the lack of long-range order is caused by vacancies at the Ni site of Ni0.85V2Se4. The non-linear temperature dependence of the resistivity as well as an enhanced value of the Sommerfeld coefficient γ=104.0(1) mJ mol−1 K−2 suggest strong electron–electron correlations in this material. First-principles calculations performed for NiV2Se4, which are also applicable to Ni0.85V2Se4, classify this material as a topological metal with Z2=(1;110) and coexisting electron and hole pockets at the Fermi level. The phonon spectrum lacks any soft phonon mode, consistent with the absence of periodic lattice distortion in the present experiments.