The extrinsic hysteresis behavior of dilute binary ferrofluids

Lihua Lin; Jian Li; Yueqiang Lin; Xiaodong Liu; Longlong Chen; Junming Li; Decai Li

doi:10.1140/epje/i2014-14102-6

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2024 Impact factor 2.2

Soft Matter and Biological Physics

Eur. Phys. J. E (2014) 37: 102
https://doi.org/10.1140/epje/i2014-14102-6

Regular Article

The extrinsic hysteresis behavior of dilute binary ferrofluids

Lihua Lin¹, Jian Li¹^*, Yueqiang Lin¹, Xiaodong Liu¹, Longlong Chen¹, Junming Li¹ and Decai Li²

¹ School of Physical Science & Technology, Southwest University, 400715, Chongqing, China
² School of Mechanical and Control Engineering, Beijing Jiaotong University, 100044, Beijing, China

^* e-mail: aizhong@swu.edu.cn

Received: 21 April 2014
Revised: 7 July 2014
Accepted: 10 October 2014
Published online: 30 October 2014

Abstract

We report on the magnetization behavior of dilute binary ferrofluids based on $\gamma$ - Fe₂O₃/Ni₂O₃ composite nanoparticles (A particles), with diameter about 11nm, and ferrihydrite ( Fe₅O₇(OH)^·4H₂O nanoparticles (B particles), with diameter about 6 nm. The results show that for the binary ferrofluids with A-particle volume fraction $\phi_{A}$ = 0.2 % and B-particle volume fractions $\phi_{B}$ = 0.1 % and $\phi_{B}$ = 0.6 %, the magnetization curves exhibit quasi-magnetic hysteresis behavior. The demagnetizing curves coincide with the magnetizing curves at high fields. However, for single $\gamma$ - Fe₂O₃/Ni₂O₃ ferrofluids with $\phi_{A}$ = 0.2 % and binary ferrofluids with $\phi_{A}$ = 0.2 % and $\phi_{B}$ = 1.0 %, the magnetization curves do not behave in this way. Additionally, at high field (750 kA/m), the binary ferrofluid with $\phi_{B}$ = 1.0 % has the smallest magnetization. From the model-of-chain theory, the extrinsic hysteresis behavior of these samples is attributed to the field-induced effects of pre-existing A particle chains, which involve both Brownian rotation of the chains’ moments and a Néel rotation of the particles’ moments in the chains. The loss of magnetization for the ferrofluids with $\phi_{B}$ = 1.0 % is attributed to pre-existing ring-like A-particle aggregates. These magnetization behaviors of the dilute binary ferrofluids not only depend on features of the strongly magnetic A-particle system, but also modifications of the weaker magnetic B-particle system.