The Electrical Characterization of Magnetic Tunneling Junction Cells Using Conductive Atomic Force Microscopy with an External Magnetic Field Generator

Abstract

We examined the tunneling current behaviors of magnetic tunneling junction (MTJ) cells utilizing conductive atomic force microscopy (AFM) interfaced with an external magnetic field generator. By introducing current through coils, a magnetic field was generated and then controlled by a current feedback circuit. This enabled the characterization of the tunneling current under various magnetic fields. The current-voltage (I-V) property was measured using a contact mode AFM with a metal coated conducting cantilever at a specific magnetic field intensity. The obtained magnetoresistance (MR) ratios of the MTJ cells were about 21% with no variation seen from the different sized MTJ cells; the value of resistance <TEX>$\times$</TEX> area (RA) were 8.5 K-12.5 K <TEX>$({\Omega}{\mu}m^2)$</TEX>. Since scanning probe microscopy (SPM) performs an I-V behavior analysis of ultra small size without an extra electrode, we believe that this novel characterization method utilizing an SPM will give a great benefit in characterizing MTJ cells. This novel method gives us the possibility to measure the electrical properties of ultra small MTJ cells, namely below <TEX>$0.1\;{\mu}m\;{\times}\;0.1\;{\mu}m$</TEX>.