FePt3中不同磁有序间的相竞争与自偏置效研究-材料科学与工程专业毕业论文.docx

Abstract This paper have investigated the influence of the chemical order to the magnetic structure and magnetic properties of FePt3．The relation of the phases of FePt3 at different chemical order and exchange bias phenomenon have been studied from theoretical calculation and experiment．The main results ofthis paper are as follows： (1)Super-cell model have been established and we have got different chemical order FePt3 by switching the site of atoms．The results of energy and magnetic moment of FePt3 three phases at different chemical order have been got by theoretical calculation and from it we can discover that：The most stable phase is AFMQl for completely ordered FePt3 and the energy difference between AFMQ I and AFMQ2 phases is smaller as chemical order decrease．Whether it is the stoichiometric ratio of FePt3 or Pt—rich FePt3，the introduction of chemical disorder can induce the appearance of AFMQ2 phase，just the the latter is more difficult．Similarly,the magnetic moment is 0 at completely ordered FePt3 but net magnetic moment exists when the chemical order decrease．From above theoretical calculated results we Call conclude that the in仃oduction of chemical disorder can induce AFMQ2 phase． (2)The FePt3 films have been fabricated by Magnetron sputter and PLD at the different temperatures and have been characterized by XRD．The chemical of films have calculated by Lorentz fitting．The results of XRD indicate that all the samples are single crystal．By calculating the chemical orde5 we can conclude that the higher preparative temperature，the higher the degree of chemical order．So the fabricated temperature affect the degree of chemical order by influence the mobility of atoms (3)The magnetic properties of FePt3 sample at different temperatures have been measured by VSM and the dependence of exchange bias on temperature has investigated．It was found that the exchange bias show different temperature dependence in different temperature ranges，suggesting AFMQ2 phase may ap