The resonance decay function method in the determination of the pre-factor of the Neel relaxation time of single-domain nanoparticles

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:323

Article; Proceedings Paper

Fannin, P. C.¹  Marin, C. N.²  Couper, C.¹ 

[1] Trinity Coll Dublin, Dept Elect & Elect Engn, Dublin 2, Ireland

[2] W Univ Timisoara, Fac Phys, Timisoara 300223, Romania

关键词: Magnetic fluid;    Dynamic susceptibility;    Ferromagnetic resonance;   

DOI  :  10.1016/j.jmmm.2010.11.014

来源: Elsevier

【 摘 要 】

In its simple form, the relaxation time of the Neel relaxation process of the magnetic moment of single-domain particles is given by tau(N)=tau(0N)exp(sigma), sigma being the ratio of anisotropy energy to thermal energy. The pre-factor, tau(0N), is normally given a value of 10(-9) s, but values ranging from 10(-8) to 10(-12) s have been reported in literature. Here, by means of the field and frequency dependence of the complex magnetic susceptibility, chi(omega,H)=chi'(omega,H)-i chi ''(omega,H), of a magnetic fluid sample, in the MHz-GHz range, in conjunction with the determination of the sample decay function, b(t), the pre-factor tau(0N) is determined. b(t) is readily obtained through the inverse Fourier transformation relationship, which exists between b(t) and chi ''(omega). (C) 2010 Elsevier B.V. All rights reserved.

【 授权许可】

Free