Dynamic properties of spin cluster glass and the exchange bias effect in BiFeO3 nanocrystals

Sining Dong, Yiping Yao, Ying Hou, Yukuai Liu, Yang Tang, Xiaoguang Li

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Abstract

A spin cluster glass behavior and a complicated exchange bias effect are observed in high quality BiFeO3 nanocrystals grown by a hydrothermal method. The dynamic properties of the spin clusters investigated by measuring the frequency dependences of ac susceptibility show that the relaxation process can be described using a power law with the glass transition temperature T g = 57K, relaxation time constant τ0 = 4.4 × 10- 10s, and critical exponent zv = 10.3 ± 1.9, consistent with a three-dimensional Ising spin glass. The exchange bias field (H EB) varies non-monotonically with temperature and achieves a minimum at Tg. The abnormal shift of hysteresis loops above Tg may be interpreted in terms of a Malozemoff's random-field model with a framework of antiferromagnetic core/spin-cluster shell structure and a two-dimensional diluted antiferromagnet in a field (2D-DAFF) model, respectively. The exchange anisotropy of the BiFeO3 nanocrystals will shed light on a possible application for magnetism related nanosized devices.

Original languageEnglish (US)
Article number385701
JournalNanotechnology
Volume22
Issue number38
DOIs
StatePublished - Sep 23 2011

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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