Mesoporous Oxide-Diluted Magnetic Semiconductors Prepared by Co Implantation in Nanocast 3D-Ordered In₂O_3–y Materials

Abstract

Mesoporous In 2 O 3−y materials have been implanted using Co ions to induce a moderate ferromagnetic response at room temperature, forming a "mesoporous oxide-diluted magnetic semiconductor" (MODMS). X-ray photoemission spectroscopy (XPS) reveals that implantation results in up to 1 at. % Co (for 6 × 10 15 ions/cm 2 at 40 keV) and 15 at. % Co (for 1 × 10 17 ions/cm 2 at 60 keV). This is in both cases accompanied by a pronounced increase in the amount of oxygen vacancies with respect to the pristine, nonimplanted, In 2 O 3−y. Further increase in the ion fluence (up to 2 × 10 17 ions/cm 2 at 60 keV) results in the collapse of the mesoporous structure, i.e., loss of the 3D-ordered porous configuration. XPS also reveals that virtually no metallic Co is formed at 40 keV, while a mixture of Co 2+ and Co 0 states is detected after implantation at 60 keV. Most of the Co 2+ is incorporated in the bixbyite structure of the In 2 O 3−y matrix. These results are consistent with previous models suggesting that the origin of the obtained ferromagnetic response in oxide-diluted magnetic semiconductors can be ascribed to ferromagnetic exchange interactions mediated by oxygen vacancies. This work constitutes the first report on MODMS prepared by nanocasting followed by implantation of transition metal ions.

Monodispersed In2O3 mesoporous nanospheres: One-step facile synthesis and the improved gas-sensing performance

“…Another approach to porous In 2 O 3 is through template route [31][32][33]. Block-polymers, SBA-15, KIT-16 silica are usually selected as the templates [34].…”

Nano-Structured Dilute Magnetic Semiconductors for Efficient Spintronics at Room Temperature

“…Mn-doped In2O3 was synthesized by solid-state methods and that composition showed magnetic moment of 2.83 μB/Mn due to tetrahedrally or octahedrally coordinated Mn 3+ in the intermediate spin state [110]. A mesoporous In2O3 semiconductor implanted with Co ions shows a measurable ferromagnetic signature at RT [111]. Co-doped In2O3 synthesized by chemical solution route showed FM at RT and Some other methods, such as 5% Fe-doped In 2 O 3 films which were pulsed laser deposited under a partial pressure of 10 −3 , 10 −5 and 10 −7 torr, respectively [107] and polarized neutron scattering measurements reveal lower magnetized Fe-rich phase located at the interface than uniformly distributed phases.…”

“…Mn-doped In 2 O 3 was synthesized by solid-state methods and that composition showed magnetic moment of 2.83 µB/Mn due to tetrahedrally or octahedrally coordinated Mn 3+ in the intermediate spin state [110]. A mesoporous In 2 O 3 semiconductor implanted with Co ions shows a measurable ferromagnetic signature at RT [111]. Co-doped In 2 O 3 synthesized by chemical solution route showed FM at RT and LT [112].…”

Evaporation-induced self-assembly synthesis of Ni-doped mesoporous SnO2 thin films with tunable room temperature magnetic properties

“…It is surprising that although many of the cutting-edge technological applications in magnetism and spintronics also rely on surface or interface magnetic phenomena, the use of nanoporous magnetic frameworks in these technologically-relevant fields has just emerged during the last few years. [33][34][35][36][37][38] During the last few years, we have reported the synthesis and magnetic characterization of TM-doped oxide semiconducting mesoporous powders prepared by nanocasting. [35][36][37] The doping with the TM confers a magnetic character to this type of materials, which can then be categorized as mesoporous oxide-diluted magnetic semiconductors (MODMS).…”