Magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM) studies on Cr/Ni nanodot arrays deposited using innovative nano-stencil method

Abstract

Nanodot arrays of Nickel (Ni) on Chromium (Cr), [Cr in two forms i. e. (Cr dot) and Cr (layer)] were fabricated by electron beam evaporation technique using nano-stencil. The deposition of a periodic dot pattern was confirmed through atomic force microscopy (AFM) imaging. The nano magnetic properties of the Cr/Ni nanodot arrays were probed using both Magnetic Force Microscopy (MFM) and Magneto-Optical Kerr Effect (MOKE) magnetometer. MOKE measurements unveiled saturated hysteresis with the exchange bias effect for the in-plane configuration and a minor hysteresis loop for the out-of-plane configuration in the Cr/Ni nanodot system. The experimental results were found to be in good agreement with the theoretical Stoner-Wohlfarth (SW) model. Additionally, the exchange bias effect was also observed in the Cr (thin film)/Ni (nanodot) system for both the in-plane and out-of-plane configurations, showing the dominating behavior of the Cr layer over the Ni dots due to its continuous layer and higher thickness. The observation of exchange bias properties was also verified through MFM measurements conducted with both positive and negative in-plane magnetic fields. Hence, this straightforward nano-stencil method holds significant promise for the streamlined production of patterned AFM/FM arrays enabling the comprehensive study of exchange bias phenomena. The magnetic properties of the Cr/Ni structure can be manipulated by depositing Cr either in nanodot form or in continuous layer form.