Structural phase transition and ferromagnetism in monodisperse 3 nm FePt particles

Authors

• Chuan-bing Rong, University of Texas at Arlington
• Narayan Poudyal, University of Texas at Arlington
• Girija S. Chaubey, University of Texas at Arlington
• Vikas Nandwana, University of Texas at Arlington
• Ralph Skomski, University of Nebraska-LincolnFollow
• Y. Q. Wu, Iowa State University
• Matthew J. Kramer, Iowa State UniversityFollow
• J. Ping Liu, University of Texas at ArlingtonFollow

Document Type

Article

Date of this Version

8-30-2007

Comments

Published by Am Inst of Physics. J. Appl. Phys. 102, 043913 2007. Copyright 2007. Permission to use. http://www.aip.org/.

Abstract

FePt nanoparticles with a size of 3 nm and thermally stable room-temperature ferromagnetism are investigated. The monodisperse nanoparticles were prepared by chemical synthesis and a salt-matrix annealing technique. Structural and magnetic characterizations confirmed the phase transition from the disordered face-centered cubic structure to the L1₀ structure with the chemical ordering parameter of 0.62±0.05. Analysis in blocking temperature and fitting of temperature dependence of switching field reveals that the transformed 3 nm nanoparticles have a magnetic anisotropy constant of (2.8±0.2) x 10⁶ J/m³, smaller than those for the bigger particles and the fully ordered L1₀ bulk phase.