Studies On Single Crystals Growth And Transports Of Topological Insulator TaSe3 And Ta-doped Weyl Semimetal MoTe2

Topological phases have attracted research attention in the area of condensed matter physics recently.From Kosterlitz-Thouless transition to TKNN topological invariant,and quantum Hall effect to quantum spin Hall effect,the concept of topology in condensed matter physics has been understood much deeper.Starting with HgTe/CdTe quantum well,various topological materials have been exploited,such as topological insulators and topological semimetals,etc.The emergence of such topological materials brings many exotic phenomena,and these materials could be an option for the material basis of the future electronic industry.Large unsaturated magnetoresistance(XMR)is an interest of transport phenomenon in solids.Such magnetoresistance with magnitude～103%is observed in topological insulator candidate TaSe3 from our high field(up to 38 T)measurements.Two oscillation modes,associated with one hole pocket and two identical electron pockets in the bulk,respectively,are detected from our Shubnikov-de Hass measurements,consistent with our first-principles calculations.With the detailed Hall measurements performed,our two-band model analysis exhibits an imperfect density ratio nh/ne≈0.9 at T<20 K,which suggests that the carrier compensations account for the XMR in TaSe3Superconductivity is a regular in the transports of condensed matter physics.We systematically studied the transports of Mo1-xTaxTe2,and observe that Mo1-xTaxTe2 exhibits the 1T’-Td structural phase transition,metal-superconductor transition and the decreasing distance between layers along c-axis,with Ta substitution increasing,similar to the case of MoTe2 under applied pressure.With the calculations carried out,we found that the calculated results match the experimental data.