Giant room-temperature magnetocapacitance in Co2+ doped SnO2 dielectric films

Abstract

The giant room-temperature magnetocapacitance is reported in the Co2+ substitutionally doped SnO2 film in which the ferromagnetism coexists with the dielectric state. The maximum magnetocapacitance is observed in the Sn0.98Co0.02O2 film in which the magnetocapacitance is as large as 0.45 at frequency of 1.0 kHz and saturated magnetic field of ∼6.0 kOe. We experimentally demonstrate that such magnetocapacitance effect correlates with the Co dopant concentration and the existence of oxygen vacancy. The electric polarization response of the oxygen vacancy–Co ion complexes to the magnetic field is attributed to the origin of the magnetocapacitance.

Microstructural Investigation, Raman and Magnetic Studies on Chemically Synthesized Nanocrystalline Ni-Doped Gadolinium Oxide (Gd1.90Ni0.10O3−δ)

“…Because of high resistivity, high dielectric constant and large band gap, rare earth oxides are the potential candidate for new generation spin filter, magnetic sensor and storage devices. 12 In recent times, the magnetic behavior of TM ion doped rare earth oxides such as Dy 1 20 So far as these authors' ' knowledge, no report of magnetic ordering was observed in Ni-doped Gd 2 O 3 till now. Considering the importance of rare earth oxides, particularly Gd 2 O 3 as Gd 3+ is S-state ion with high value of free ion magnetic moment ($ 7.94 l B ) and dielectric constant 11 and in continuation of our earlier work, here we report the preparation, structural refinement, morphology, Raman spectroscopy and magnetic behavior of Ni 2+ ion doped gadolinium oxide with composition Gd 1.90 Ni 0.10 O 3Àd (GNO) where the percentage of doping is same with results of previous studies.…”

Variation of structural, optical and magnetic properties with Co-doping in Sn1−xCoxO2 nanoparticles

“…Such a decrease of the E g induced by TM doping has been reported in Co-and Mn-doped SnO 2 [13,17], as well as other TMdoped oxide semiconductors [6,21], and has been ascribed to the sp-d exchange interactions between the band electrons and the localized d electrons of the TM ions substituting Sn ions [22,23]. In addition, two additional absorption peaks at around 440 and 650 nm arise for the Co-doped samples, which may be attributed to the absorption of trapped electrons by Co 2 þ ions [24] and d-d transitions of Co 2 þ ions [25], respectively. Moreover, in all absorption spectra, no typical peak of about 1050 nm corresponding to Co 3 O 4 [19] was detected.…”

Tunable room temperature ferromagnetism in Sn0.93Fe0.05M0.02O2−σ (M=Sb/Mg): The role of electron- and hole-doping

“…In the DMS-based materials, an additional degree of freedom of the electron (spin) can be realized by doping ferromagnetic 3d transition metals, i.e., Fe, Co, Mn, etc. Various transition-metal-doped systems such as Ge, GaAs, TiO 2 , SnO 2 and ZnO have been reported to show robust ferromagnetic response [4][5][6][7][8][9][10]. Specifically, room temperature ferromagnetism (RTFM), which favors the device applications, has been achieved in several wide bandgap metal oxides, e.g., TiO 2 , SnO 2 , ZnO and In 2 O 3 .…”