Development of dynamic aurora pulsed laser deposition equipped with reflection high-energy electron diffraction and effects of magnetic fields on room-temperature epitaxial growth of NiO thin film

Abstract

Pulsed laser deposition (PLD) with an electromagnet (dynamic aurora PLD) and reflection high-energy electron diffraction (RHEED) was developed by installing an 11-tuned solenoid coil in a vacuum chamber. This method achieved thin film deposition under a magnetic field of up to 120 mT using dc current of 1,200 A. The electromagnet is a solenoid coil, which produces a magnetic field that is proportional to an electric field without saturation of the magnetic field. This PLD method enables in situ observation of the crystal structure of the thin film surface after turning the electromagnet off, but without breaking vacuum. Many reports have described studies of PLD in a magnetic field. For most such studies, permanent magnets have been used to apply a magnetic field to the plume. Nevertheless, when doing so, carrying out in-situ observation using RHEED is difficult because the magnetic field deflects the electron beam. This case study examined effects of magnetic field application to the plume on the in-plane orientation and resistivity of a NiO thin film deposited on a MgO(001) single crystal at room temperature (25 °C). Results demonstrate that the in-plane orientation (epitaxial growth) is unchanged, whereas thin film resistivity decreases exponentially with the magnetic field intensity during deposition. These results suggest that the Ni3+ ion concentration can be expected to increase exponentially with the magnetic field during deposition. The room-temperature resistivity of the NiO thin film deposited under a 120 mT magnetic field was 112 Ω cm.