Single-crystal Growth And Physical Properties Of Ternary Low-dimensional Transition-metal Tellurides TaPdTe₅ And TaPtTe₅

In recent years,the unique physical properties and great application potential,exploring topological quantum materials protected by various symmetry has become an important direction in the field of condensed matter physics.So,most topological nontrivial materials have two-dimensional or three-dimensional structural characteristics,while topological materials with quasi-one-dimensional structure are rare.In this paper,the ternary low-dimensional transition metal tellurides Ta Pd Te₅ and TaPtTe₅ were studied respectively through single crystal growth and physical properties measurement.Firstly,the synthesis and physical properties measurement of a novel layered ternary telluride Ta Pd Te₅ with quasi-one-dimensional Pd Te₂ chain were studied.The compound crystallizes in layered orthorhombic structure with space group Cmcm.The analysis of Hall resistivity using the two-band model shows that the hole carriers with high mobility dominate the transport at low temperature.When the magnetic field is applied along the crystal to the b-axis,the in-plane magnetoresistance(MR)shows obvious anisotropy.We also measured the magnetoresistance of the strong magnetic field along the c axis.At low temperature,it follows the power law of the magnetic field dependence,and there is no saturation behavior.The de Haas-van Alphen oscillation shows of one small Fermi surface pocket with non-trivial Berry phase.Shubnikov-de Haas(Sd H)oscillations occur in magnetic fields above 28.5 T,and at low temperatures.Two efficient quality m⁽⁹⁾were extracted from the Sd H oscillation data.The first principle calculation reveal a topological Dirac cones in the surface status,especially the topology index indicating that Ta Pd Te₅ is a topological nontrivial material.In addition,TaPtTe₅ single crystal was also grown,and the anisotropic magnetoresistance,Hall effect and quantum de Haas-van Alphen(d Hv A)oscillation in TaPtTe₅ single crystal were studied.The single crystal has a layered crystal structure of quasi-one-dimensional Pt Te₂ chain.TaPtTe₅ exhibits anisotropic magnetoresistance and nonlinear Hall effect at low temperature.Two main oscillation frequencies are obtained by analyzing d Hv A oscillation.The corresponding effective mass and non-zero Berry phase indicate the topologically non-trivial band structure in TaPtTe₅,which is further confirmed by first-principles calculations.The above results show that TaPtTe₅ is also a topological Dirac material with quasi-one-dimensional chain structure similar to its sister compounds Ta Pd Te₅ and Ta Ni Te₅.