Research Of Topological Properties Of HoSbTe And PrPd_0.82Bi₂

In the past two decades,the concept of topology has been introduced into condensed matter physics from the branch of mathematics,which is extended to solid band theory and has greatly promoted the development of condensed matter physics.From the discovery of quantum Hall effect to the 3D topological insulators and the rapid evolution of topological semimetals,various topological electronic states are uncovered gradually.Topological materials have abundant and novel electronic structure,which has great application prospect for the fields of spintronics and topological quantum computing.Recently,many novel physical phenomena have been found in layered topological materials,such as the quantum anomalous Hall effect,axion insulator state,the high order topological insulator,and so on.In our work,combining the single crystal growth method and physical properties measurement,we have systematically research on the layered antiferromagnetic topological electronic materials,such as HoSbTe,PrPd_0.82Bi₂,and so on.Furthermore,other high-quality single crystals of layered topological materials have been synthesized.The mainly contents as follows:1.New compound HoSbTe has been found for the first time and single crystals have been successfully grown.Combination the experiment and theoretical calculation,the structure,magnetic and electronic transport properties of the magnetic topological candidate HoSbTe have been systematically studied.This compound crystallizes in a tetragonal layered structure(space group:P4/nmm,no.129),in which the Ho-Te bilayer is separated by the square-net Sb layer.The physical properties measurement shows that a paramagnetic-antiferromagnetic(PM-AFM)phase transition appears at?4 K.Combining the first-principle calculations with ARPES measurement of band structure,we find that HoSbTe is a weak topological insulator,providing a new platform to investigate the interplay between magnetic and topological fermionic properties.2.We report the physical properties,crystalline and magnetic structures of singe crystals of a new layered antiferromagnetic(AFM)material PrPd_0.82Bi₂.The measurements of magnetic properties and heat capacity indicate a PM-AFM phase transition at T_N?7 K.A large Sommerfeld coefficient of 329.23 m J·mol^-1·K^-2 is estimated based on the heat capacity data,implying a possible heavy-fermion behavior.The magnetic structure of this compound is investigated by a combined study of neutron powder and single-crystal diffraction.It is found that an A-type AFM structure with magnetic propagation wavevector6)=(0 0 0)is formed below T_N.The Pr³⁺magnetic moment is aligned along the crystallographic c-axis with an ordered moment of 1.694(3)?_B at 4 K,which is smaller than the effective moment of the free Pr³⁺ion of 3.58?_B.PrPd_0.82Bi₂ can be grown as large as 1 mm×1 cm in area with a layered shape,and is very easy to be cleaved,providing a unique opportunity to study the interplay between magnetism,possible heavy fermions,and superconductivity.3.We have successfully synthesized a series of high-quality layered single crystals,such as Pt Bi₂,Nb_2n+1Si_nTe_4n+2,Nb₃Ge Te₆,La Sb Te,and so on.And we have conducted out many study for the structure and physical properties.By ARPES,a giant anisotropic3D Rashba-like spin splitting directly observed in the P31m Pt Bi₂;the inherited weak topological insulator signatures in the topological hourglass semimetal in Nb₃Ge Te₆;the realization of a genuine topological nodal-line semimetal in La Sb Te.The discoveries from the experiment have expended the research field of topological electronic state.The layered material studied in this paper has the natural cleavage advantage and the interaction between magnetism and topological band,which not only provides a new idea for the study of strange quantum phenomena,but also provides a new research material for the preparation of topological electronic devices and has very important scientific value.