Magnetism of Zn-doped SnO2: Role of surfaces

Abstract

Surface effects on the magnetization of Zn-doped SnO2 are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO2 show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO2. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO2. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped (110) surface reveals that the spin polarization of the host band occurs primarily from p-orbitals of bridging oxygen atoms and the Zn atom itself contributes minimally. The present work provides a key understanding on the role played by the surfaces in inducing the magnetism of doped nanoparticles and thin films.

Defect ferromagnetism in SnO2:Zn2+ hierarchical nanostructures: correlation between structural, electronic and magnetic properties

“…The incorporation of zinc in SnO 2 and the stability of other common defects is however sensitive to the specic surface where these defects formed. Pushpa et al 25 have studied the formation energies and magnetic moments for various defects in the bulk, at the surface and in sub-surface layers, in both Snrich and O-rich conditions. In general it is easier to form both Sn and O vacancies at surfaces than in the bulk, and the (001) surface is preferred to the (110) surface.…”

“…Interestingly, the Zn atom on the (110) surface does not contribute to the induced moment directly. 25 The moment arises from the nearest neighbour bridging oxygen and minimally from the in-plane oxygen or the Sn atom. It is further understood that while the moment arises from the polarization of the partially lled oxygen bands, the occurrence of ferromagnetism or antiferromagnetism (AFM) in these bands depends on the separation between the holes on oxygen atoms surrounding the V Sn defect.…”

Zn dopant effect on growth, morphology, texture and mechanical properties of SnO2 thin films

“…Doped tin oxide is used for solar cells [1], gas sensor [2], photo catalysis [3], pollutants detection [4], anode for ion lithium batteries [5] as quantum dots [6,7], ferromagnetic [8] and photoconductive devices. Nowadays, Zn doped SnO2 show promising applications for high temperature semiconductor [9] and optoelectronics devices [10], both properties are being improved by tuning the amount and type of dopants. In solar energy research, Zn doped SnO2 nanoparticles (NPs) are being used as photo anode material to induce negative shift in the flat-band potential to increase the isoelectric point in dye-sensitized solar cell [11].…”

First-principles insight into the surface magnetism of Cu-doped SnO2(110) thin film

“…The discovery of ferromagnetism with a Curie temperature (T C ) of 650 K and a giant magnetic moment (7.5 AE 0.5) m B /Co in Co-doped SnO 2 lm 4 has aroused great interest in researching for new ferromagnetic semiconductors based on host material of SnO 2 . [5][6][7][8][9][10][11][12][13][14][15][16] There have been encouraging reports of ferromagnetic states in Cu-doped SnO 2 systems in theoretical simulations [12][13][14][15] and experimental observations, [14][15][16] hence, Cu-doped SnO 2 magnetic material provides a new route to explore the origin of ferromagnetism as well as the underlying physical mechanism.…”

“…While in the Cu-doped SnO 2 nanowires the room temperature ferromagnetism can be attributed to both surface defects and oxygen vacancies. 16 Recently, the surface magnetism induced by Rh-, 7 Zn-, 8 Codoped 17 (110) surface of SnO 2 was investigated. Rahman et al studied the surface magnetism induced by a C-doped (001) surface.…”