We report the superconductivity of a new quaternary compound ThMo_(2)Si_(2)C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr_(2)Si_(2)C-type structure with cell parameters o...We report the superconductivity of a new quaternary compound ThMo_(2)Si_(2)C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr_(2)Si_(2)C-type structure with cell parameters of a = 4.2296A and c = 5.3571 A. An interlayer Si–Si covalent bonding is suggested by the atomic distance. The electrical resistivity and magnetic susceptibility measurements indicate a Pauli-paramagnetic metal with dominant electron-electron scattering in the normal-state. Bulk superconductivity at 2.2 K is demonstrated with a dimensionless specific-heat jump of △C/γnT = 0.98. The superconducting parameters of the critical magnetic fields, coherence length, penetration depth, and superconducting energy gap are given.展开更多
Anomalous Nernst effect, as a thermal partner of anomalous Hall effect, is particularly sensitive to the Berry curvature anomaly near the Fermi level, and has been used to probe the topological nature of quantum mater...Anomalous Nernst effect, as a thermal partner of anomalous Hall effect, is particularly sensitive to the Berry curvature anomaly near the Fermi level, and has been used to probe the topological nature of quantum materials. In this work, we report the observation of both effects in the ferromagnetic Weyl-semimetal Fe_(3-δ)GeTe_(2) with tunable Fe vacancies. With decreasing Fe vacancies,the anomalous Hall conductivity evolves as a function of the longitudinal conductivity from the hopping region to the region where the intrinsic Berry curvature contribution dominates. Concomitant evolutions in the anomalous Nernst signal and the anomalous off-diagonal thermoelectric coefficient are observed below the Curie temperature, displaying a unique sign change caused by the Fe vacancies. Combining these results with first-principles calculations, we argue that the Fe-vacancy concentration plays a unique role in simultaneously tuning the chemical potential and ferromagnetism, which in turn controls the Berry curvature contribution in this family of ferromagnetic topological semimetals.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0303002)the Natural Science Foundation of Shandong Province (Grant Nos. ZR2019MA036, and ZR2016AQ08)。
文摘We report the superconductivity of a new quaternary compound ThMo_(2)Si_(2)C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr_(2)Si_(2)C-type structure with cell parameters of a = 4.2296A and c = 5.3571 A. An interlayer Si–Si covalent bonding is suggested by the atomic distance. The electrical resistivity and magnetic susceptibility measurements indicate a Pauli-paramagnetic metal with dominant electron-electron scattering in the normal-state. Bulk superconductivity at 2.2 K is demonstrated with a dimensionless specific-heat jump of △C/γnT = 0.98. The superconducting parameters of the critical magnetic fields, coherence length, penetration depth, and superconducting energy gap are given.
基金supported by the National Natural Science Foundation of China (Grant Nos. U1932155, 11874136, 11874137, and U19A2093)the National Key Projects for Research and Development of China (Grant No. 2019YFA0308602)+1 种基金the Key R&D Program of Zhejiang Province China (Grant No. 2021C01002)supported by an open program from Wuhan National High Magnetic Field Center (Grant No. 2016KF03)。
文摘Anomalous Nernst effect, as a thermal partner of anomalous Hall effect, is particularly sensitive to the Berry curvature anomaly near the Fermi level, and has been used to probe the topological nature of quantum materials. In this work, we report the observation of both effects in the ferromagnetic Weyl-semimetal Fe_(3-δ)GeTe_(2) with tunable Fe vacancies. With decreasing Fe vacancies,the anomalous Hall conductivity evolves as a function of the longitudinal conductivity from the hopping region to the region where the intrinsic Berry curvature contribution dominates. Concomitant evolutions in the anomalous Nernst signal and the anomalous off-diagonal thermoelectric coefficient are observed below the Curie temperature, displaying a unique sign change caused by the Fe vacancies. Combining these results with first-principles calculations, we argue that the Fe-vacancy concentration plays a unique role in simultaneously tuning the chemical potential and ferromagnetism, which in turn controls the Berry curvature contribution in this family of ferromagnetic topological semimetals.
