Oxidation and annealing process: Morphological change and nanocontact MR in spin valves with FeCo-AlOx NOL spacer

Yohei Shiokawa, Megumi Shiota, Yoshiyuki Watanabe, Takahiko Otsuka, Masaaki Doi, Masashi Sahashi

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


We studied the formation mechanism of ferromagnetic nanocontacts (NCs) around 1-2 nm in diameter in thin AlOx nano-oxide layer (NOL) through in situ conductive atomic force microscopy (c-AFM), which is the only method suitable for measuring morphological changes in features this small. Spin valves (SVs) with Fe0.5Co0.5NCs in AlOx NOL fabricated by ion-assisted-oxidation (IAO) irradiated onto 1.3-nm-thick Al had nanocontact magnetoresistance (NCMR) characteristics with the MR ratio of 5% for 1 Ω μm2. According to measurements with c-AFM, these NCs were mostly located at the valleys between the AlOx grains or the edge of the grain. In other words, NCs were formed in the oxidation and cohesion process of Al by the IAO. Moreover, we found that the high-temperature annealing process improved the MR ratio to around 10% for 0.5 Ω μm 2. The high-temperature annealing process may involve the AlO x morphological change and have led the Al atoms in NCs to migrate to AlOx by combining with oxygen as impurities. Then, the morphological changes and migration of Al caused NCs to be the low resistivity and the short length.

Original languageEnglish
Article number6028127
Pages (from-to)3470-3473
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number10
Publication statusPublished - 2011 Oct


  • Conductive atomic force microscopy (c-AFM)
  • magnetoresistance
  • morphological change
  • nanocontact (NC)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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