Study On The Preparation And Properties Of Antiperovskite GaCMn₃Epitaxial Thin Film

Antiperovskite compounds have similar crystal structure with perovskite material. The antiperovskite AXMn3(X=Ga, Zn, Cu, Ge and Sn, A=N, C) show different and diverging physical properties, such as negative thermal expansion(NTE), nearly zero temperature coefficient of resistivity (TCR),magnetostriction, magnetocaloric effect, giant magnetoresistance, spin-glass behavior and so on. What is more, it also attracts a lot of research interest because of its great potential applications. In addition, this kind of material also has rich physical content, such as the expansion of narrow band effect, three-dimensional spin frustration based on the octahedral of sharing angle, close correlation among lattice, spin, and charge,etc.At present,the properties of AXMn3bulk (polycrystalline sample) have been extensively studied. The properties of AXMn3bulk can be controlled through doping and the relevant theory has been gradually established. On this basis, the film fabrication and its physical property research should be necessary in order to throw light on the mechanism of substantive characteristics and make it possible to create variety of electronic and magnetic devices.In this paper, we grow GaCMn3(GCM)thin film samples on the LaA103(LAO),(LaA103)0.3(Sr2AlTa06)0.7(LAST),SrTiO3(STO) single crystal substrate by pulsed laser deposition, and studied the effect of parameters such as substrate temperature,film thickness and epitaxial strain on the films properties on the films properties and structure.The main content of this thesis are listed as follows:Chapter1: We mainly present the AXMn3crystal structure and its research history.We describe the mechanism of doping effects on structure and properties of AXMn3bulk material.Then we list the thin film preparation technologies and low dimensional effect on the structure and physical properties of thin films.Fianlly,we discussed the prospect of antiperovskite in the future.Chapter2: We introduce the preparation of GaCMn3target using vacuum high temperature solid phase reaction method. Compared with the results reported in the literature, our target material has excellent crystal structure and physical properties, which provides us with much convenience to grow films. By the way, we have introduced the film preparation methods and the characterization methods of the sample.Chapter3:The structure and magnetoelectric properties of GCM/LAO film grown in different preparation conditions (substrate temperature and laser energy) are studied.The films showed obvious multi-orientation structures and the preparation temperature affected the orientation of films.After a detailed structural analysis, we believe that the preparation temperature factors and substrate factors competed with each other during film preparation and both of them determine the growth orientation of the films. the magnetoelectric properties of films are affected by the stress and thermal expansion from the substrate.Chapter4:We found that the (220)-orientation structure exsist even the thickness of the film is less than50nm.The strain and thickness effect of GaCMn3films are systematically studied. Comparing epitaxial films of different thickness, we hypothesized that the different magnetic properties between films and bulk are mainly caused by the stress and thermal expansion from the substrate during the heating and cooling process.