Room temperature ferromagnetic Cr–Ni codoped ZnO diluted magnetic semiconductors synthesized by hydrothermal method under high pulsed magnetic field

Pulse magnetic field-assisted hydrothermal method was used for the preparation of Cr–Ni codoped ZnO diluted magnetic semiconductors. XRD analysis reveals that all the samples have hexagonal wurtzite structure. HRTEM, EDS measurements and XPS results ensure that the divalent Cr and Ni ions have incorporated in the wurtzite host matrix without any detectable impurity phase formed. M–H and ZFC/FC curves of the samples reveal the enhancement of ferromagnetism resulted from the magnetic field processing. XPS measurement and Raman scattering spectra indicate that the content of oxygen vacancies in the sample increases with pulse magnetic field processing. According to the bound magnetic polaron model, this may be the reason for the sample with magnetic field processing having better ferromagnetism than that without field processing.