Oxygen Vacancy-Induced Room Temperature Ferromagnetism and Magnetoresistance in Fe-Doped In₂O₃ Films

Abstract

The (In 1−x Fe x ) 2 O 3 films (0 ≤ x ≤ 0.09) were prepared by RF-magnetron sputtering. Structural, magnetic and transport properties of the films were investigated systematically both experimentally and theoretically. X-ray absorption spectroscopy (XAS) and multiple-scattering ab initio theoretical calculations reveal that Fe dopant atoms are substitutionally incorporated into In 2 O 3 lattice with a mixed-valence (Fe 2+ /Fe 3+ ) and form Fe In1 +2 V O complex. All the films display room temperature ferromagnetism and the saturated magnetization (M s ) increases monotonically with the increase of Fe concentration. The Mott variable range hopping (VRH) transport behavior dominates the conduction mechanism of the films at low temperature, confirming that the carriers are localized. The Fe doping has profound effects on the positive and negative MR contributions. The positive MR contribution becomes more pronounced with Fe doping, reflecting the occurrence of spin polarization and stronger s−d exchange interaction. The bound magnetic polarons (BMPs) associated with oxygen vacancy can be considered to play an important role in achieving the ferromagnetic order of the (In 1−x Fe x ) 2 O 3 films. The variation of Ms with Fe doping has a strong correlation with the localization radius ξ of carriers and the characteristic hopping temperature T 0 , indicating that the change of localization effect can remarkably influence the ferromagnetic order of the (In 1−x Fe x ) 2 O 3 films.

Oxygen Vacancy Induced Room-Temperature Metal–Insulator Transition in Nickelate Films and Its Potential Application in Photovoltaics

“…This changes the Ni e g orbital occupation and may affect the magnetic order. Moreover, the orbitals of electrons locally trapped by an oxygen vacancy would overlap with the d shells of the neighboring transition metal (TM), and the formation of TM–V O –TM (V O denotes the oxygen vacancy) groups may also play a role in achieving ferromagnetic ordering. − Further experimental and theoretical investigations are needed to address this issue. The larger spin splitting is also a signal of larger U / W .…”

Room-Temperature Ferromagnetic Enhancement and Crossover of Negative to Positive Magnetoresistance in N-Doped In2O3 Films

“…It is obvious that N-doping has profound effects on the positive and negative contributions of MR. The crossover phenomenon from negative to positive MR was also observed in Fe-doped In 2 O 3 films and Mn-doped ZnO films, etc. , These results suggest that the N-doping-induced RT ferromagnetism has similar behavior to that induced by TM-doped oxide semiconductors.…”

Dielectric, electrical conduction and magnetic properties of multiferroic Bi0.8Tb0.1Ba0.1Fe0.9Ti0.1O3 perovskite compound

“…On the other hand, oxygen defects could also increase the magnetization by introducing Fe 2þ into the ferromagnetic order across Fe 3þ -O 2À -Fe 2þ . 40 Furthermore, during the high-temperature annealing process, the canting angles in samples were further 41 modified by the interaction between the external magnetic field and the uncompensated spins in the canted antiferromagnetic order, which may be the main reason causing the net magnetization to increase.…”