• Title/Summary/Keyword: energy harvest

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MBE growth and magnetic properties of epitaxial FeMn2O4 film on MgO(100)

  • Duong, Van Thiet;Nguyen, Thi Minh Hai;Nguyen, Anh Phuong;Dang, Duc Dung;Duong, Anh Tuan;Nguyen, Van Quang;Cho, Sunglae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.318.2-318.2
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    • 2016
  • FeM2X4 spinel structures, where M is a transition metal and X is oxygen or sulfur, are candidate materials for spin filters, one of the key devices in spintronics. Both the Fe and M ions can occupy tetrahedral and octahedral sites; therefore, these types of compounds can display various physical and chemical properties [1]. On the other hand, the electronic and magnetic properties of these spinel structures could be modified via the control of cation distribution [2, 3]. Among the spinel oxides, iron manganese oxide is one of promising materials for applications. FeMn2O4 shows inverse spinel structure above 390 K and ferrimagnetic properties below the temperature [4]. In this work, we report on the structural and magnetic properties of epitaxial FeMn2O4 thin film on MgO(100) substrate. The reflection high energy electron diffraction (RHEED) and X-ray diffraction (XRD) results indicated that films were epitaxially grown on MgO(100) without the impurity phases. The valance states of Fe and Mn in the FeMn2O4 film were carried out using x-ray photoelectron spectrometer (XPS). The magnetic properties were measured by vibrating sample magnetometer (VSM), indicating that the samples are ferromagnetic at room temperature. The structural detail and origin of magnetic ordering in FeMn2O4 will be discussed.

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Giant Perpendicular Magnetic Anisotropy of a Fe(001) Surface: A Density Functional Study

  • Odkhuu, D.;Rhim, S.H.;Yun, Won Seok;Hong, S.C.
    • Proceedings of the Korean Magnestics Society Conference
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    • 2013.12a
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    • pp.29-29
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    • 2013
  • We predict agigantic perpendicular magnetocrystalline anisotropy (MCA) in Fe (001) capped by 5d transition metal (TM) overlayers by using first principles calculations. Analysis of atom-by-atom contribution to MCA reveals that gigantic MCA as large as 11 meV/TM originates not from Fe atoms but from the 5d TMs through the strong spin-orbit coupling. More specifically, it is the hybridization between TM and Fe d orbitals that also induces non-negligible magnetic moments in TM. Furthermore, spin-channel decompositions of MCA matrix with and without the presence of Fe substrate identify the electronic origin of the perpendicular MCA that the down-down channel contribution plays the most crucial role for the sign changes of MCA of TM overlayers upon the hybridization with Fe-3d.

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Experiment on the Charge and Discharge of Thermal Energy for Under-Water Harvest-Type Ice Storage System (수중 하베스트형 빙축열시스템의 축방냉 특성 실험)

  • Kim, J.D.
    • Journal of the Korean Solar Energy Society
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    • v.22 no.2
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    • pp.11-17
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    • 2002
  • This paper is concerned with the development of a new method for making, separating ice and storage floated ice by installing an evaporation plate at under-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating an ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. Developed new harvest-type method shows good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, however these components are not necessary in a new method. In this study ice storage systems are experimentally investigated to study the charge and discharge of thermal energy. The results show the applicable possibility and performance enhancement of a new type.