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Magnetism and Transport Properties of Mn and 3d Transition Metal Compound Films Grown via Molecular Beam Epitaxy 원문보기

  • 저자

    DUONG ANH TUAN

  • 학위수여기관

    울산대학교

  • 학위구분

    국내박사

  • 학과

    물리학과

  • 지도교수

    Sunglae Cho (조성래)

  • 발행년도

    2014

  • 총페이지

    106 p.

  • 키워드

    Magnetism 3d transition metal MBE growth Transport properties;

  • 언어

    eng

  • 원문 URL

    http://www.riss.kr/link?id=T13540264&outLink=K  

  • 초록

    The 3d transition metals and their compounds are of significant interest, due to the typical characters and their promising practical applications. In ordinary condition, some 3d transition metal such as Fe, Co, and Ni exhibit a ferromagnetic behavior while Mn and Cr exhibit an antiferromagnetic behavior. However, under impact of expansion in lattice volume, Mn and Cr can become ferromagnetic materials. The 3d transition metal compounds are also very plentiful in research and application. In this dissertation author made attempts to grow Mn thin film on BaTiO3 substrate, Intermetallic compounds FeGa alloy films on the semiconductor substrates, and Bi2Fe4O9-Fe3O4 nanocomposite films on LaAlO3 substrate using MBE technique to investigate the magnetism and transport properties under low-dimensional growth. The modification of electrical and magnetic properties of Mn thin film by controlling the degree of a structural deformation using unique four different crystal structures of BaTiO3 below 400 K were observed. Magnetism switching from antiferromagnetic (with zero magnetic moment) to ferrimagnetic order (with magnetic moment up to 0.66μB/Mn at 320K) in Mn film was observed. Modification of resistivity and magnetization of Mn film correlate to structural phase transition of BaTiO3 are discussed. In FeGa alloy thin films, we investigate the magnetism and transport properties of Fe100-xGax (x= 10.5 and 24,3) thin films on GaAs (001) substrate. Epitaxial Fe-Ga thin films in disordered bcc α-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The MS decreased from 1371 to 1105 kA/m with increasing the Ga concentration from 10.5 to 24.3% at room temperature. The temperature dependent resistivity showed metallic behavior and the resistivity of low Ga concentration is larger than that of high Ga concentration. We also studied about magnetism and anomalous Hall effect of Fe100-xGax (x= 40 and 50) alloy films on GaSb (001). The results showed that an epitaxial film with bcc a-Fe crystal structure (A2) is observed in Fe60Ga40 film, while an impure Fe3Ga phase with DO3 structure is appeared in Fe50Ga50 thin film. The Fe60Ga40 film showed in-plane magnetic anisotropy while Fe50Ga50 film exhibited out-of-plane magnetic anisotropy. A clear hysteresis trend in Hall resistance was observed on Fe50Ga50 film relative to out-of-plane magnetic anisotropy. In Bi2Fe4O9-Fe3O4 nanocomposite thin film on LaAlO3 substrate, SEM and XRD results confirmed that nanocomposite films were formed as inserting orthorhombic-phase of lamellae Bi2Fe4O9 in fcc-phase of in-plane nanorod-like Fe3O4 matrix. The shift of TV to lower temperature in nanocomposite films was attributed to the presence of Bi2Fe4O9 component. The observation of TN at 260 K in the magnetization curve possibly results from the superposition behavior of ferrimagnetic Fe3O4 with antiferromagnetic Bi2Fe4O9 components. The results of this study could prove interesting and important in developing and potential applications of 3d transition metal and 3d transition metal compounds films in spintronic devices.


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