Magnetic Properties of Al–SiC Co-Sputtered Films Grown by Radio Frequency Sputtering

Room-temperature ferromagnetism was observed in the Al–SiC co-sputtered films fabricated by radio frequency (RF) sputtering. When the annealing temperature (Ta) was increased from 800 to 1100 °C, the ferromagnetic ordering was present with the formation of Al–C bonds. Both annealing and Al-doped the films can improve the crystallization of SiC and induce long-range magnetic order in the Al–SiC co-sputtered films. Experiments show that the Al solubility was less than 0.8 at% in SiC matrix. As a possible explanation for the existence of local magnetic moment in Al-doped SiC, unpaired spins arise in a conversion from sp³ to the sp³/sp² hybridization. The partial Si–C bonds in SiC were converted to Al–C bonds when the trivalent aluminum entered into Si sites. Al atoms introduce some net spins in Al doped film with the calculated integrated spin density 0.467 _B. The structural defects produced by Al-doping have provided an exciting possibility of nonmagnetic atoms-doped to control the spin moments and induce ferromagnetism in wide-gap semiconductor.