Enhanced spin-dependent charge transport of Co-(Al-fluoride) granular nanocomposite by co-separate sputtering

Yang Cao, Nobukiyo Kobayashi, Yi Wen Zhang, Shigehiro Ohnuma, Hiroshi Masumoto

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Spin-dependent charge transport behavior involving the recently discovered tunnel-type magneto-dielectric (TMD) and magnetoresistance (TMR) effects was studied in Co-(Al-fluoride) granular nanocomposites. By setting a changeable partition height (t = 1-4 cm) on a substrate holder in a conventional co-sputtering (CS) deposition system, we developed a co-separate sputtering (CSS) method to fabricate Co-(Al-F) granular nanocomposites. XPS analysis shows that the Al content remains balanced between the Al metal and Al-F compounds by controlling t. This phenomenon can be attributed to the magnetron plasma interference from the two target sources. Fittings between TMR and normalized magnetization suggest that the CSS films with clear granular structures may have high spin polarization. Compared with the CS samples (t = 0 cm), the CSS films with t = 4 cm show enhanced charge transport properties with a maximum TMD ratio (0.5%) and TMR ratio (7.2%) under a magnetic field of H = 10 kOe. This study demonstrates that the Al-F tunnel barrier between Co granules plays an essential role in controlling the charge transport behavior and will be of significance for applications in field sensors and impedance-tunable devices with large magnetic-field response.

Original languageEnglish
Article number133903
JournalJournal of Applied Physics
Volume122
Issue number13
DOIs
Publication statusPublished - 2017 Oct 7

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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