Transition from diamagnetic to ferromagnetic state in laser ablated nitrogen doped ZnO thin films

Abstract

Transition from room temperature diamagnetic to ferromagnetic state in N doped ZnO (ZnO:N) films grown by pulsed laser deposition with tunable energy density has been identified. ZnO:N films deposited with moderate laser energy density of 2.5 J/cm2 are single phase and nearly defect free having N dopant substitution at O sites in ZnO lattice, exhibiting intrinsic ferromagnetism. When energy density reduces (<2.5 J/cm2), defects in ZnO:N film degrades ferromagnetism and exhibit diamagnetic phase when grown at energy density of 1.0 J/cm2. Growth kinetics, which in turn depends on laser energy density is playing important role in making transition from ferromagnetic to diamagnetic in ZnO:N films.

Nitrogen-doped semiconducting oxides. Implications on photochemical, photocatalytic and electronic properties derived from EPR spectroscopy

“…65,66 On the basis of theoretical forecasts, N-ZnO based structures have also been considered as dilute magnetic semiconductors showing ferromagnetic interactions among nitrogen centers 67,68 and experimental observation of such a behaviour have already been reported in the literature. 69 Various techniques have been used to introduce nitrogen into the ZnO matrix, depending on the morphology of the bare system nitrogen has been successfully introduced in ZnO single crystals grown through a chemical vapor deposition process and successively annealed in a N 2 ow at high temperature (see below). ZnO nanorods have been produced on uorine tin oxide substrates and nitrogen has been introduced via ion implantation technique.…”

Electrocatalytic Properties of ZnO Thin Film Based Biosensor for Detection of Uric Acid

“…Ambient pressures (100% O 2 ) were varied in the range of 1-100 mT to analyze the effect of growth kinetics on biosensing response. In our previous work, it has been reported that the laser fluence influences the defect profile in ZnO films, and native defects are maximum in ZnO thin films deposited at low laser energy density (1.0-1.5 J/cm 2 ) [17]. Since presence of defects in metal oxide matrix enhanced the electron communication property and are useful for obtaining good biosensing response characteristics [14]; ZnO thin films are grown at low laser fluence (1.2 J/cm 2 ) in the present work for biosensing applications [17].…”

“…In our previous work, it has been reported that the laser fluence influences the defect profile in ZnO films, and native defects are maximum in ZnO thin films deposited at low laser energy density (1.0-1.5 J/cm 2 ) [17]. Since presence of defects in metal oxide matrix enhanced the electron communication property and are useful for obtaining good biosensing response characteristics [14]; ZnO thin films are grown at low laser fluence (1.2 J/cm 2 ) in the present work for biosensing applications [17]. Since the ablated species require minimum energy to settle down on the desired nucleating sites on the substrates, ZnO thin films were intentionally deposited without heating the substrates so that large number of defects may be introduced.…”

Morphology-Dependent Room-Temperature Ferromagnetism in Undoped ZnO Nanostructures

“…This promoted search for DMS based on alternative dopants. Manifestation of RTFM has also been undertaken by doping with non-magnetic dopants such as H [26,[98][99][100][101][102][103][104][105][106][107][108][109][110]124,125], N [126,127], C [128][129][130][131], and S [47,78]. Interestingly, the observation of RTFM strongly suggests the presence of a spin-split band with a non-zero spin-orbit coupling in H-ZnO single crystals [100].…”