專題演講

2018/01/18(Thu)     14:00 -16:00    5th Floor(1st meeting room)

Title

Transport properties, electronic structures and Fermi surfaces of Dirac nodal-line semimetals, ZrSiSe and ZrSiTe

Speaker

Mr. Yu-Che Chiu

Department of Physics, Florida State University

Abstract

We report a study on the geometry of the Fermi surface (FS) of ZrSi(Se,Te) via the de Haas-van Alphen effect (dHvA), whose electronic dispersion was reported to display a line of Dirac nodes within their Brillouin zone. For both compounds we find that their FSs agree well with Density Functional Theory (DFT) calculations. In contrast to ZrSiTe, DFT finds that the nodal Dirac line is close to the Fermi level in ZrSiSe which displays a very small
residual resistivity and pronounced four-fold symmetric magnetoresistivity as a function of field orientation. The transport lifetime in ZrSiSe is found to be 102−103
times larger than its quasiparticle lifetime indicating that its charge carriers are protected against backscattering under zero-field, as previously reported for Cd3As2. The quasiparticle lifetime in ZrSiSe is
found to be angle-dependent displaying a minimum for fields along the c-axis. Therefore, the “butterfly” magnetoresistivity observed in ZrSiSe, but not in ZrSiTe, seems to result from the magnetic field-induced suppression of this protection against backscattering, with this effect becoming particularly effective as the field is aligned along the inter-planar direction.