Effects of ion-beam irradiation on the L1 0 phase transformation and their magnetic properties of FePt and PtMn Films

Chih Huang Lai, Sheng Huang Huang, Cheng Han Yang, C. C. Chiang, S. H. Liou, D. J. Sellmyer, M. L. Yan, L. Yuan, T. Yokata

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


In this paper, we illustrate how to modify the structure and magnetic properties of L1 0 FePt and PtMn films using ion-beam irradiation. Highly ordered L1 0 FePt and PtMn phases were achieved directly by using 2 MeV He-ion irradiation without conventional post-annealing. A high ion-beam current density (∼μA/cm 2) was used to achieve direct beam heating on samples. This irradiation-induced heating process provides efficient microscopic energy transfer and creates excess point defects, which significantly enhances the diffusion and promotes the formation of the ordered L1 0 phase. In-plane coercivity of FePt films greater than 5700 Oe could be obtained after disordered FePt films were irradiated with a He-ion dose of 2.4×10 16 ions/cm2. The direct ordering of FePt took place by using ion-irradiation heating at a temperature as low as 230°C. In PtMn-based spin valves, an L1 0 PtMn phase, a large exchange field and a high giant magnetoresistance (GMR) ratio (11%) were simultaneously obtained by using He-ion irradiation. On the other hand, Ge-ion and O-ion irradiation completely destroyed the ferromagnetism of FePt and the GMR of PtMn-based spin valves, respectively.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium Proceedings
Number of pages12
StatePublished - 2006
Event2005 Materials Research Society Fall Meeting - Boston, MA, United States
Duration: Nov 28 2005Dec 1 2005

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


Conference2005 Materials Research Society Fall Meeting
Country/TerritoryUnited States
CityBoston, MA

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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