Fig. 1: Evaluation of εr for epitaxial MgO-MTJ with thick MgO tunnel barrier.
From: Dielectric constant of MgO tunnel barrier with epitaxial strain
a Schematics of the epitaxial stack used in the present study. b Schematic of the equivalent circuit used for the analysis. c f dependence of Z’ (gray circles) and Z” (orange circles) for devices with tMgO = 4.0 nm and S = 144 μm2. d f dependence of −(Z”)−1 for devices with tMgO = 4.0 nm. The fitted lines are shown as black lines. e S dependence of Cp for devices with 4.0 ≤ tMgO ≤ 10.0 nm. The colored closed circles represent Cp values obtained from the frequency dependence of Z” considering Rs. The black open circles represent Cp values obtained from the impedance at 1 MHz, ignoring Rs. f tMgO dependence of εr for epitaxial MgO tunnel barriers with 4.0 ≤ tMgO ≤ 10.0 nm.
