Effects of grain size on reversible and irreversible domain wall displacements in La0.7Sr0.3MnO3perovskite

✍ Scribed by Wang, Jinhui ;Liu, Gongqiang ;Jiang, Xiaolong ;Du, Youwei

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 210 KB
• Volume: 202
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200420019

✦ Synopsis

Abstract

In this work, the permeability spectra of La~0.7~Sr~0.3~MnO~3~ perovskite with mean grain size (D) ranging from 1200 to 45 nm have been investigated at 293 K. The spectra exhibit a typical relaxation, relating to reversible domain wall motions. The quasi‐static permeability (μ~e~) decreases from 87 to 11 with D, while relaxation frequency f~r~ increases from 205 kHz to 231 MHz. As the amplitude of the ac field h~0~ exceeds the domain wall pinning field h~p~, irreversible domain wall motions will be activated. The increments of permeability with increasing h~0~ can be explained using the Rayleigh law. With reducing D from 1200 to 140 nm, h~p~ increases from 1.8 to 2.3 A/m and the Rayleigh constant decreasing from 2.15 × 10^–1^ to 4.66 × 10^–2^ (A/m)^–1^. The grain size dependence of μ~e~ and f~r~ has been discussed related to the demagnetizing field induced by distributed air gaps between grains. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)