Faculty of Physics, Hanoi University of Science

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Friday Seminar 15/01/2016

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Department of Computational Physics and Applied Informatics respectfully invites you to our monthly Seminar:

Seminar

Date: Fri. 15th Jan./Time: 9 am – 11 am / Place: Room 408F, Building T1

334 NguyễnTrãi, Thanh Xuân, HàNội

Kính mời mọi người quan tâm đến dự / Everyone is welcome !

(Keynote) Speaker 1 (9am-10am): Dr. Le Tuan Tu (Department of Low Temperature Physics, Faculty of Physics, VNU University of Science)

Title: Magnetic nanowires: Synthesis, properties and applications

Abstract: High aspect-ratio magnetic nanomaterials, especially magnetic nanowire arrays have generated growing interest in the scientific community due to their potential applications in magnetic sensors, high-density magnetic recording, bioengineering, and magneto-electronic devices. The magnetic properties of the nanowires are governed by several material parameters, such as diameter, length, composition and direction of an externally applied field. The magnetic properties in Co, CoNiP, Au/Co nanowires arrays were investigated. All the samples were prepared by electrodeposition method using the polycarbonate templates. We investigated the influence of varying the pH values (pH = 2.0 – 6.5) on the magnetic properties of ordered CoNiP nanowires. The effects of varying diameter (d = 100–600 nm) and external applied magnetic field (HA = 0 – 0.21 T) on the magnetic properties of ordered CoNiP nanowires are also investigated. The deposition potential of the electrolyte was investigated by cyclic voltammetry. The morphology of the magnetic nanowires was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with high-resolution TEM (HR-TEM). The nominal composition of the nanowires was determined by energy dispersive spectroscopy (EDX). The crystal structure was analyzed by X-ray diffraction (XRD). Magnetic hysteresis loops (M-H) were recorded at room temperature using a vibrating sample magnetometer (VSM). The aminothiphenol (4-ATP) functionalized multisegment magnetic nanowires surfaces were characterized by Raman spectra. The mixture of fcc and hcp polycrystalline phases of the CoNiP based nanowires has been indicated by the XRD pattern. The lattice spacing of the CoNiP layers were 0.205 nm. The magnetic properties of CoNiP nanowires were improved when the pH values was pH values changed from 2.0 to 6.5. The values HC rapidly increased with the pH values changed from 2.0 to 5.5 and the maximum coercivity is 1936 Oe. The anisotropy of the samples are quasi-one-dimensional anisotropic. The relationship between Mr/Ms ratio and magnetic field applied are calculated. The Mr/Ms ratio was rapid increased when the magnetic field changed from 0 Oe to 2100 Oe. The anisotropy field and uniaxial anisotropy values dependent on magnetic field applied and diameter are also calculated.

Reference:Materials Transactions 56, 1327 (2015); Sensors 15, 5687 (2015); VNU J. of Science, Math-Phys 31 (1S), 52 (2015); Communication in Physics 24 (3S1), 103 (2014).

Speaker 2 (10:15 am-10:50am): Mr. Le Anh Dung(Department of Theoretical Physics, Faculty of Physics, VNU University of Science)

Title:Glauber – type (eikonal) representation for high energy scattering problem

Abstract:Glauber – type representation, or usually called eikonal representation, for high energy scattering amplitude is an interesting problem which receives concerns of many authors. This representation has been used to analyze experimental data as well as to deal with some theoretical problems such as Coulomb – hadron interference. Hitherto, there have been significant attempts on this branch of the quantum theory of scattering. In this report, we will present some results of our group related to the problem together with introducing in brief two approaches toward this problem which have been widely used in many studies in general and in our study in particular: path integral and direct (equation – solving) methods.

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