Superparamagnetic Co36C64 granular film

✍ Scribed by Hao Wang; M.F. Chiah; W.Y. Cheung; S.P. Wong

• Book ID: 103884809
• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 298 KB
• Volume: 344
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2003.09.244

✦ Synopsis

Nanocomposite Co-C thin films of about 15 nm thick were prepared by pulsed filtered vacuum arc deposition. The films were characterized by X-ray photoelectron spectroscopy, non-Rutherford backscattering spectrometry, X-ray diffraction, and magnetic force microscopy. The as-deposited films were amorphous. After annealing at 350 C for 1 h in vacuum (o10 À3 Pa), the films were found to consist of nanocrystalline Co grains encapsulated in carbon. The superparamagnetism of the annealed Co 36 C 64 film was demonstrated by the measurement of DC susceptibility and magnetic hysteresis using a SQUID magnetometer. The superparamagnetic relaxation blocking temperature was marked to be about 12 K by the peak of the zero-field-cooled magnetization under a field of 100 Oe. The magnetic properties of these annealed granular Co-C films transform from superparamagnetism to ferromagnetism when the Co concentration increases.