Functional spinel oxide heterostructures on silicon

Functional spinel oxides (general formula AB2O4 , ferromagnetic for instance) can be monolithically integrated by epitaxy on silicon thanks to a spinel template-layer, the cation-deficient spinel gamma-Al2O3, similarly to the monolithic integration on silicon of functional perovskite oxides (general formula ABO3 , that can be ferroelectric, piezoelectric, etc..) by using a SrTiO3 template-layer epitaxially grown on Si(001).

These novel all-spinel heteroepitaxial structures on silicon have been demonstrated with the ferrimagnetic spinel CoFe2O4 (CFO) films grown by pulsed laser deposition (PLD) on an ultrathin gamma-Al2O3 template-layer grown on Si(111) by oxide molecular beam epitaxy (MBE). We obtain flat (111)-oriented epitaxial CFO films, with only two in-plane domains induced by the gamma-Al2O3 layer, which are ferromagnetic at room temperature with a high saturation magnetization. These results open perspectives for using high-quality functional spinel layers on silicon for monolithic devices such as spin filters for instance.

Contact: Romain BACHELET

“Functional spinel oxide heterostructures on silicon”, Romain Bachelet, Patricia de Coux, Bénédicte Warot-Fonrose, Vassil Skumryev, Gang Niu, Bertrand Vilquin, Guillaume Saint-Girons and Florencio Sánchez, CrystEngComm. 16, 10741 (2014)

ICMAB-CSIC, ICREA and UAB (Barcelone); CEMES-CNRS (Toulouse)

Schematic view representing the fabrication of all-spinel heteroepitaxial structure on silicon. Demonstration was done here with ferrimagnetic spinel CoFe2O4 (CFO) films deposited by PLD on ultrathin gamma-Al2O3 epitaxial template-layer elaborated by MBE on Si(111). CFO films, reproducing the crystalline qualities of the template, have then good magnetic properties (see magnetization hysteresis loops).
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