X-ray Photoelectron Spectroscopy Study Of ThN Block Layers Superconducting Compound And MnBi₂Te₄

For most iron-based superconductors,the parent compound itself has antiferromagnetic fluctuations,and suppressing the antiferromagnetic fluctuations by chemical or physical means can induce superconductivity,which has become an important means to explore new types of superconductors.However,for the Th N barrier layer superconducting compound Th Fe As N,the parent compound does not have antiferromagnetic fluctuations,and can exhibit superconductivity as high as 30 K without any treatment.In order to explore the origin of its superconductivity,we analyzed the structure,magnetic properties,transport and XPS data of the iron-based superconductor Th Fe As N precursor and doped electronic samples.This artical found that as electrons are doped,the chemical pressure inside the crystal is gradually released,and the superconductivity also disappears.Until the conventional superconductor Th Ni As N is formed,the superconductivity reappears.Through the analysis of the transport data,we found that Th Fe As N and its doped samples are not only metallic,but a minimum point of resistance(T_min)appears as the temperature decreases.After the T_minpoint,the resistance increases with temperature increasing.The resistance exhibits the semiconducting behavior of rising as the temperature decreases,possibly due to the occurrence of a Kondo-like scattering.At the same time,in order to explore the difference between the electronic states of superconducting and non-superconducting samples,this artical performed XPS analysis on the samples.Through data comparison,this artical found that with the incorporation of Ni atoms,both Fe2p and Th4f shifted to higher binding energy positions.It is all due to the increase in electron density around the two elements caused by electron doping.The inherent magnetic and topological properties of antiferromagnetic topological insulators make them potential materials that can realize the quantum anomalous Hall effect at relatively high temperatures.Similar to the superconductivity,the quantum anomalous Hall effect can also realize the dissipation of electron transport.In this paper,the topological insulator Mn Bi₂Te₄with antiferromagnetic properties has been successfully synthesized through the solid-state reactions.Through magnetic and transport tests,this paper has determined that its Neel temperature is 24.5 K,and spin-flop occurs under a magnetic field of 1.8 K and 35000 Oe.In theory,there are still many materials in the Mn Bi₂Te₄family that can achieve quantum anomalous Hall effect(such as Mn Bi₂Se₄),but they have not been successfully synthesized in experiments.In order to explore the reasons,this article has studied the growth mode of Mn Bi₂Te₄through XPS testing and other methods.Determined its intercalation growth method based on structural symmetry.In terms of structure,?-Mn Te and Bi₂Te₃as the precursor are both layered structures,and the lattice matching of the two materials is as high as 96.6%,which provides a prerequisite for intercalation growth.Furthermore,this paper obtained that the chemical valence states of Mn and Te in the precursor Mn Te were consistent with those in Mn Bi₂Te₄after peaking the XPS spectra.It indicates that Mn Te is directly inserted into Bi₂Te₃with five layers as a unit to generate Mn Bi₂Te₄with seven layers as a unit,and there is electron transfer between the two materials,which is believed to be the driving force for the interactive growth of the two precursors.