Europium nitride is semiconducting and contains non-magnetic 3+, but sub-stoichiometric EuN has Eu in a mix of 2+ and 3+ charge states. We show that at 2+ ~concentrations near 15-20% EuN is ferromagnetic with a Curie temperature as high as 120 K. The
3+ ~polarization follows that of the 2+, confirming that the ferromagnetism is intrinsic to the EuN which is thus a novel diluted magnetic semiconductor. Transport measurements shed light on the likely exchange mechanisms.
A major challenge for the next generation of spintronics devices is the implementation of ferromagnetic-semiconductor thin films as spin injectors and detectors. Spin-polarised carrier injection cannot be accomplished efficiently from metals, and cou
pled with the rarity of intrinsic ferromagnetic semiconductors this has driven intensive study of diluted magnetic semiconductors. Chief among these is the doped III-V compound (Ga,Mn)As. These materials suffer from a number of drawbacks; they (i) require magnetic-ion doping well above the solubility limit, and (ii) must be hole doped to above the degenerate limit, preventing independent control of the carrier concentration and charge sign. Here we demonstrate the first epitaxial growth of a recently-characterised intrinsic ferromagnetic semiconductor, GdN, on silicon substrates, providing an essential step on the way to integrate new spintronics functionalities into Si-based technology. The films have been characterised as regards their growth toward fully relaxed GdN, the density and mobility of their carriers, and their magnetic behaviour.
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