Interface effect of magnetic properties in Ni nanoparticles with a hcp core and fcc shell structure

Seongmin Choo, Kyujoon Lee, Younghun Jo, Seon Mi Yoon, Jae Young Choi, Jea Young Kim, Jea Hoon Park, Kyoung Jin Lee, Jong Heun Lee, Myung Hwa Jung

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We have fabricated hexagonal close-packed (hcp) Ni nanoparticles covered by a face-centered cubic (fcc) Ni surface layer by polyol method. The magnetic properties have been investigated as a function of temperature and applied magnetic field. The magnetic behavior reveals that the system should be divided magnetically into three distinct phases with different origins. The fcc Ni phase on the shell contributes to the superparamagnetism through a wide temperature range up to 360 K. The hcp Ni phase at the core is associated with antiferromagnetic nature below 12 K. These observations are in good agreement with the X-ray absorption spectroscopy and magnetic circular dichroism measurements. In our particular case, the unique hcp core and fcc shell structure gives rise to an additional anomaly at 20 K in the zero-field-cooled magnetization curve. Its position is barely affected by the magnetic field but its structure disappears above 30 kOe, showing a metamagnetic transition in the magnetization versus magnetic field curve. This new phase originates from the magnetic exchange at the interface between the hcp and fcc Ni sublattices.

Original languageEnglish
Pages (from-to)6126-6130
Number of pages5
JournalJournal of Nanoscience and Nanotechnology
Volume11
Issue number7
DOIs
Publication statusPublished - 2011 Jul

Keywords

  • Core-Shell Structure
  • Fcc Ni Nanoparticles
  • Hcp Ni Nanoparticles
  • Magnetic Properties

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Biomedical Engineering
  • Materials Science(all)
  • Condensed Matter Physics

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