Local strain-induced ferromagnetism in inhomogeneous Fe-implanted silicon carbide

Abstract

Despite an intense research on diluted magnetic semiconductors since twenty years ago, the origin and nature of observed ferromagnetism in these materials remain controversial, the presence of transition metal precipitates hindering to reveal unambiguously the intrinsic ferromagnetic behavior of the semiconducting matrix. In this work, we have investigated the magnetic properties of Fe-doped SiC, composed of Fe-rich nanoparticles and some diluted Fe atoms in the SiC matrix. By a careful analysis of the experimental magnetization data, a magnetic contribution from the diluted Fe atoms in the SiC matrix was evidenced, with a Curie temperature (TC) value of ∼115 K. Such a value is much higher than those reported in similar III-V diluted magnetic semiconductors such as a few at.% Mn-doped InP (TC = 20–40 K). This magnetic ordering temperature of the diluted Fe atoms is shown to be independent of the amorphous or crystalline state of the SiC matrix, but depends strongly on the Fe-rich nanoparticle size, with a drastic reduction of TC down to 45 K observed in the presence of Fe-rich nanoparticles with diameter higher than 10 nm.