Eur. Phys. J. B (2017) 90: 227
https://doi.org/10.1140/epjb/e2017-80264-7

Regular Article

Apparently enhanced magnetization of Cu(I)-modified γ-Fe₂O₃ based nanoparticles

¹ School of Physical Science and Technology, Southwest University, Chongqing 400715, P.R. China
² State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, P.R. China

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

Received: 8 May 2017
Received in final form: 19 September 2017
Published online: 20 November 2017

Abstract

Using a chemically induced transition method in FeCl₂ solution, γ-Fe₂O₃ based magnetic nanoparticles, in which γ-Fe₂O₃ crystallites were coated with FeCl₃⋅6H₂O, were prepared. During the synthesis of the γ-Fe₂O₃ nanoparticles Cu(I) modification of the particles was attempted. According to the results from both magnetization measurements and structural characterization, it was judged that a magnetic silent “dead layer”, which can be attributed to spin disorder in the surface of the γ-Fe₂O₃ crystallites due to breaking of the crystal symmetry, existed in the unmodified particles. For the Cu(I)-modified sample, the CuCl thin layer on the γ-Fe₂O₃ crystallites incurred the crystal symmetry to reduce the spin disorder, which “awakened” the “dead layer” on the surface of the γ-Fe₂O₃ crystallites, enhancing the apparent magnetization of the Cu(I)-modified nanoparticles. It was determined that the surface spin disorder of the magnetic crystallite could be related to the coating layer on the crystallite, and can be modified by altering the coating layer to enhance the effective magnetization of the magnetic nanoparticles.