Magnetic Properties of Enhanced Permeability Dielectrics for Nanomagnetic Logic Circuits

Abstract

Enhanced permeability dielectric (EPD) samples were fabricated in an ultra-high-vacuum magnetron sputtering system, and their magnetic properties were studied by a variable-temperature vibrating sample magnetometer. EPDs were fabricated with layers of CoFe forming uniform particles separated by MgO dielectric as insulator. The optimal sample has peak relative low-field permeability (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) of 452, saturation magnetization (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) of 636 emu/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and magnetization at 100 Oe (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100 Oe</sub> ) of 398 emu/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Effect of low temperature is discussed, and measurements show that the EPD remains superparamagnetic at 173 K; μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> , M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> and M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100 Oe</sub> values at reduced temperatures are higher than those at room temperature. The sample is ferromagnetic at 100 K.