Enhancement of Ferromagnetism in Nonmagnetic Metal Oxide Nanoparticles by Facet Engineering

Abstract

Ferromagnetism in semiconducting metal oxide nanoparticles has been intensively investigated due to their potential applications in spintronics, information storage, and biomedicine. Ferromagnetism can be produced in nonmagnetic metal oxide nanoparticles by a variety of methods or factors, but the saturated magnetization is typically of the order of 10 emu g and too small to be useful in practice. In this work, it is demonstrated theoretically and experimentally that stronger ferromagnetism can be achieved in undoped nonmagnetic metal oxide semiconductors by exposing some specific polar crystal facets with carvings of special bonds via the interaction with underlying vacancies. In O microcubes with completely enclosed {001} polar facets show two orders of magnitude enhancement at room temperature compared to nanoparticles with an irregular morphology. The surface magnetic domains on the {001} facets account for the significantly enhanced ferromagnetism. The technique and concept described here can be extended to other types of metal oxide nanostructures to spur their application to spintronics.

Investigating the Vibrational, Magnetic and Dielectric Properties, and Antioxidant Activity of Cerium Oxide Nanoparticles

“…In this case, the results suggest the existence of a mixed phase of ferromagnetic and paramagnetic in the CeO-2 sample, in agreement with previous papers [60,61]. It was demonstrated that the presence of surface oxygen deficiency determines the magnetic ordering within cerium oxide nanostructures [11,13,18,62,63]. The XPS data indicated a higher content of oxygen vacancies in CeO-1, which exhibited a dominant ferromagnetic response, whereas in the CeO-2 sample having a higher content of adsorbed oxygen the ferromagnetism was diminished [42].…”

Theory of Ferromagnetism in Reduced ZrO2–x Nanoparticles

“…For this reason, metal oxide nanoparticles (NPs) and nanostructures represent ideal systems to obtain FM at high Curie temperatures ( T C > RT). 30 Recently, a FM behavior at RT has been reported for undoped ZrO 2 nanostructures. 2 The phenomenon has been attributed to the presence of surface oxygen vacancies (V O ).…”

Achieving Direct Z-Scheme Charge Transfer through Constructing 2D/2D α-Fe2O3/CdS Heterostructure for Efficient Photocatalytic CO2 Conversion

“…Simultaneously, such an evident shift to the lower binding energy also occurred in the Fe–O bond of the O 1s spectrum. Considering that the decrease of binding energy manifests the weakened electron screening effect the resulted from the increased electron density, ,− such a shift of binding energy suggests the electron migration from CdS to α-Fe 2 O 3 after constructing nanohybrid and may induce the interfacial electric field directed from CdS to α-Fe 2 O 3 . These results demonstrate the intimate contact and superior electronic coupling at the heterointerface between CdS NSs and α-Fe 2 O 3 NSs.…”