NMR Investigation of the WTe2 Weyl Semimetal below the Topological Transition Temperature
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NMR investigations are performed on 125Te nuclei of WTe2 Weyl topological semimetal at temperatures of 41 and 293 K. The measurements were carried out using a Bruker Avance 500 NMR pulse spectrometer. The 125Te NMR spectra for a WTe2 single crystal are obtained for the orientation of crystal axis c parallel and perpendicular to the quantizing field. A complicated form of the spectra was related to the presence of four nonequivalent positions of tellurium atoms in the crystalline structure of WTe2. The longitudinal magnetization recovery was studied after the pulse saturation for particular spectral lines. An exponential character of relaxation is revealed. The frequency shift and width of spectral lines were found to be insignificantly different at the two temperatures, while the times of nuclear spin-lattice relaxation at 41 K exceeded approximately by 30 times the corresponding times measured at room temperature. The strong temperature dependence of the relaxation is supposedly related to the contribution of the Weyl quasi-particles below the topological phase transition.
Keywords:Weyl semimetals nuclear magnetic resonance topological phase transition thermoelectrics
The measurements were performed with the use of the equipment of the centers of the Research Park of St. Petersburg State University “Center for diagnostics of functional materials for medicine, pharmacology, and nanoelectronics” and “X-ray diffraction studies.”
This work was supported by the Russian Foundation for Basic Research (projects nos. 19-57-52001, 19-07-00028, and 17-52-52008) in the framework of the governmental task of the Ministry of Education and Science of the Ru-ssian Federation (theme “Spin,” no. AAAA-A18-118020290104-2) with a partial support of the Government of the Russian Federation (regulation no. 211, contract no. 02.A03.21.0006).
CONFLICT OF INTERESTS
The authors declare the absence of any conflicts of interest.
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