Effect of viscosity on the AC magnetization of magnetic nanoparticles under different AC excitation fields

Takashi Yoshida, Takuru Nakamura, Oji Higashi, Keiji Enpuku

Research output: Contribution to journalArticle

Abstract

For in vivo applications of magnetic nanoparticles (MNPs), environment viscosity is one of the most important parameters that determines their AC magnetization. In this study, we investigate the effect of viscosity on the AC magnetization of MNPs under different AC excitation field conditions. We show that the AC M − H curve and harmonic magnetization spectrum strongly depend on the viscosity for a small excitation field intensity and low excitation frequency, while they are insensitive to the viscosity for a large excitation field intensity and high excitation frequency. We then show that the difference in the AC magnetization between these cases can be qualitatively explained by taking the field dependent Brownian fB(Hac) and Néel fN(Hac) frequencies into account. The frequencies are obtained from numerical simulations based on the Fokker-Planck equations. Finally, we show that an excitation field with a relatively large intensity and a frequency f that satisfies fB(Hac) « f ≤ fN(Hac) is suitable for the magnetic fluid hyperthermia (MFH) application.

LanguageEnglish
Pages334-339
Number of pages6
JournalJournal of Magnetism and Magnetic Materials
Volume471
DOIs
Publication statusPublished - Feb 1 2019

Fingerprint

Fokker Planck equation
Magnetic fluids
Magnetization
Viscosity
Nanoparticles
Computer simulation

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Effect of viscosity on the AC magnetization of magnetic nanoparticles under different AC excitation fields. / Yoshida, Takashi; Nakamura, Takuru; Higashi, Oji; Enpuku, Keiji.

In: Journal of Magnetism and Magnetic Materials, Vol. 471, 01.02.2019, p. 334-339.

Research output: Contribution to journalArticle

@article{4b8b964049264619ace72a3da9b73f86,
title = "Effect of viscosity on the AC magnetization of magnetic nanoparticles under different AC excitation fields",
abstract = "For in vivo applications of magnetic nanoparticles (MNPs), environment viscosity is one of the most important parameters that determines their AC magnetization. In this study, we investigate the effect of viscosity on the AC magnetization of MNPs under different AC excitation field conditions. We show that the AC M − H curve and harmonic magnetization spectrum strongly depend on the viscosity for a small excitation field intensity and low excitation frequency, while they are insensitive to the viscosity for a large excitation field intensity and high excitation frequency. We then show that the difference in the AC magnetization between these cases can be qualitatively explained by taking the field dependent Brownian fB(Hac) and N{\'e}el fN(Hac) frequencies into account. The frequencies are obtained from numerical simulations based on the Fokker-Planck equations. Finally, we show that an excitation field with a relatively large intensity and a frequency f that satisfies fB(Hac) « f ≤ fN(Hac) is suitable for the magnetic fluid hyperthermia (MFH) application.",
author = "Takashi Yoshida and Takuru Nakamura and Oji Higashi and Keiji Enpuku",
year = "2019",
month = "2",
day = "1",
doi = "10.1016/j.jmmm.2018.09.127",
language = "English",
volume = "471",
pages = "334--339",
journal = "Journal of Magnetism and Magnetic Materials",
issn = "0304-8853",
publisher = "Elsevier",

}

TY - JOUR

T1 - Effect of viscosity on the AC magnetization of magnetic nanoparticles under different AC excitation fields

AU - Yoshida, Takashi

AU - Nakamura, Takuru

AU - Higashi, Oji

AU - Enpuku, Keiji

PY - 2019/2/1

Y1 - 2019/2/1

N2 - For in vivo applications of magnetic nanoparticles (MNPs), environment viscosity is one of the most important parameters that determines their AC magnetization. In this study, we investigate the effect of viscosity on the AC magnetization of MNPs under different AC excitation field conditions. We show that the AC M − H curve and harmonic magnetization spectrum strongly depend on the viscosity for a small excitation field intensity and low excitation frequency, while they are insensitive to the viscosity for a large excitation field intensity and high excitation frequency. We then show that the difference in the AC magnetization between these cases can be qualitatively explained by taking the field dependent Brownian fB(Hac) and Néel fN(Hac) frequencies into account. The frequencies are obtained from numerical simulations based on the Fokker-Planck equations. Finally, we show that an excitation field with a relatively large intensity and a frequency f that satisfies fB(Hac) « f ≤ fN(Hac) is suitable for the magnetic fluid hyperthermia (MFH) application.

AB - For in vivo applications of magnetic nanoparticles (MNPs), environment viscosity is one of the most important parameters that determines their AC magnetization. In this study, we investigate the effect of viscosity on the AC magnetization of MNPs under different AC excitation field conditions. We show that the AC M − H curve and harmonic magnetization spectrum strongly depend on the viscosity for a small excitation field intensity and low excitation frequency, while they are insensitive to the viscosity for a large excitation field intensity and high excitation frequency. We then show that the difference in the AC magnetization between these cases can be qualitatively explained by taking the field dependent Brownian fB(Hac) and Néel fN(Hac) frequencies into account. The frequencies are obtained from numerical simulations based on the Fokker-Planck equations. Finally, we show that an excitation field with a relatively large intensity and a frequency f that satisfies fB(Hac) « f ≤ fN(Hac) is suitable for the magnetic fluid hyperthermia (MFH) application.

UR - http://www.scopus.com/inward/record.url?scp=85054188909&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85054188909&partnerID=8YFLogxK

U2 - 10.1016/j.jmmm.2018.09.127

DO - 10.1016/j.jmmm.2018.09.127

M3 - Article

VL - 471

SP - 334

EP - 339

JO - Journal of Magnetism and Magnetic Materials

T2 - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

ER -