Ferromagnetic Enhancement in ZnTiO3 films induced by Co doping

Abstract

Abstract ZnTiO3 is a promising wide band gap semiconductor material due to its actual and potential applications in catalysts, nonlinear optics, luminescent materials, microwave dielectrics, gas sensors, and solar cells. In this report, Co-doped ZnTiO3 nanocrystal films were prepared on Si wafers using chemical solutions, and their structural, optical, and magnetic properties were investigated. Co2+ ion in the films was confirmed via X-ray photoelectron spectroscopy. X-ray diffraction demonstrated that Co-doped ZnTiO3 films are a hexagonal space group (No. 148), and the lattice constant a increases but c decreases with the increasing Co content. All of the films show weak room temperature ferromagnetic order, and their saturated magnetizations increase slowly with increasing Co composition, which may be related to bound magnetic polarons. The average radius of bound magnetic polaron is approximately 15 A. The optical parameters of the films were extracted via spectroscopy ellipsometry. At 532 nm, n, defined as the refractive index of the films, gradually increases as the Co increases. With Co content x from 0.00 to 0.10, EOBG (the optical band gap of the Co-doped ZnTiO3) decreases from 4.37 to 4.10 eV, S0 (the average oscillator strength) decreases from 7.90 × 10−5 to 6.33 × 10−5 nm−2, and λ0 (the average oscillator wavelength) decreases from 0.0156 to 0.0134 nm, but E0/S0 (the electro-optical parameter) of the samples increases from 1.01 × 10−14 to 1.46 × 10−13 eVm2. The present report will be constructive for possible applications of ZnTiO3 in magnetic-optical devices.