• Title/Summary/Keyword: Magnetic Dependence

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Magnetic Field Dependence of Brownian Motion in Iron-oxide Nanoparticles (산화철 나노입자의 브라운 운동에 대한 자기장 의존성 연구)

  • Jung, Eun Kyung;Yoon, Seok Soo;Kim, Dong Young
    • Journal of the Korean Magnetics Society
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    • v.26 no.1
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    • pp.13-18
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    • 2016

  • The ac magnetic susceptibility was measured in iron-oxide nanoparticles with average size of 26 nm, which were uniformly dispersed in organic solvent. The ac magnetic susceptibility measured under zero magnetic fields was well fitted with Debye relaxation model and the relaxation frequency was 370 Hz. The relaxation frequency of the nanoparticles coincided with relaxation time of the Brownian motion, which is due to the viscosity of the liquid medium in which magnetic nanoparticles dwell. The Brown relaxation frequencies were linearly increased with magnetic field.

  • https://doi.org/10.4283/JKMS.2016.26.1.013 인용 PDF KSCI

Study on the Linear Magnetic Field Sensor Using ΔE in Amorphous Ribbon (비정질 리본의 ΔE 특성을 이용한 선형 자기센서에 관한 연구)

  • Park, S.Y.;Kim, C.G.;Ryu, K.S.;Kim, D.Y.
    • Journal of the Korean Magnetics Society
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    • v.23 no.6
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    • pp.205-208
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    • 2013

  • The width dependence of Delta E has been studied by impedance resonance method in Fe-rich amorphous ribbon of as received state. It can be explained by single domain model include effective magnetic field $H_{eff}$ and demagnetization factor $N_d$. Wider width ribbon's effective is smaller than narrow it. Young's modulus also smaller than narrow width. These result well agreement in calculation. It has been also studied that linear magnetic field sensor using width dependence of Delta E under the field range 0 Oe~80 Oe. The sensitivity of the sensor was found to be 95 Hz/Oe.

  • https://doi.org/10.4283/JKMS.2013.23.6.205 인용 PDF KSCI

Theoretical considerations on the giant magnetoimpedance effect in amorphous ribbons

  • Phan, Manh-Huong;Nguyen Cuong;Yu, Seong-Cho
    • Proceedings of the Korean Magnestics Society Conference
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    • 2003.06a
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    • pp.60-61
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    • 2003

  • Theoretical considerations on a giant magneto-impedance (GMI) effect in amorphous ribbons (i.e., thin films) have been made in terms of the expressions of effective permeability and impedance derived in the frame of classical electrodynamics and ferromagnetism. The dependence of GMI effect on the external do magnetic field (H$\_$ext/) and the frequency of alternating current are simulated and discussed in the knowledge of energy conversion consisting of the current energy loss, the ferromagnetic energy consumption, and the magnetic energy storage in the film. The obtained results are summarized as follow: (a) As frequency f< 20 ㎒, the real part of effective permeability (${\mu}$′) changes slightly. The peak of the ${\mu}$′curve always locates at H$\_$ext/=H$\_$ani/ - the anisotropy field. However, the peak value of ${\mu}$′ tends to increase with increasing frequency in the frequency range of 11-20 ㎒. (b) In the frequency range, f= 21-23 ㎒, a negative peak additionally appears. Meanwhile, both the positive and negative peak values rapidly increase with increasing frequency and their peak positions shift towards a high H$\_$ext/. (c) The positive peak value of ${\mu}$′ starts to decrease at f= 29 ㎒ and its negative peak does so at about 35 ㎒. Then, both peaks keep such a tendency and their peak positions move to high H$\_$ext/, as increasing frequency. (d) The dependence of the imaginary part of effective permeability (${\mu}$") on the external dc magnetic field and the frequency of the alternating field indicates that there is only one peak involved in ${\mu}$" for the whole frequency range. (e) The impedance vs. magnetic field curves at various frequencies show that there is a critical value of frequency around f= 18-19 ㎒ where the transition between two frequency regimes occurs; the one (low frequency) in which ${\mu}$′ predominantly contributes to the GMI effect and the other (high frequency) in which ${\mu}$" determines the GMI effect.

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A Study on the Magnetic Properties and Microstructures of Mn-Ir/Ni-Fe/Zr Muti layers with Various Compositions, Thicknesses and Base Pressures (Mn-Ir의 조성과 두께 및 초기진공도에 따른 Mn-Ir/Ni-Fe/Zr 다층막의 자기적특성과 미세구조 연구)

  • 노재철;최영석;이경섭;김용성;서수정
    • Journal of the Korean Magnetics Society
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    • v.9 no.3
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    • pp.166-172
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    • 1999

  • The magnetic properties between Mn-Ir antiferromagnetic layer and Ni-Fe ferromagnetic layer have been investigated in Mn-Ir/Ni-Fe/Zr on Si wafer formed by magnetron sputtering. Mn-Ir was sputtered from Ir chips and Mn target using D.C. power, Ni-Fe and Zr were deposited from Ni-Fe and Zr targets using D.C. power under Ar atmosphere. We studied the dependence of the magnetic properties on Ir content of Mn-Ir layer for Mn-Ir/Ni-Fe bilayer, and obtained the highest $H_ex$ of 219 Oe and the low $H_c$ of 30 Oe. And then focused on the effect of base pressure for Mn-Ir containing multilayers. Our experimental data showed that if the base pressure is higher than $3.0{\times}10^{-6}\;Torr$, the exchange anisotropy of Mn-Ir/Ni-Fe/Zr disappeared probably due to the grain refining of Mn-Ir film. In addition we have studied the dependence of Zr buffer on magnetic properties of Mn-Ir/Ni-Fe/Zr multilayers, and observed that Zr buffer about (111) texture and lower $H_c$ of Mn-Ir/Ni-Fe/Zr multilayer.

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