Magnetic Properties of Enhanced Permeability Dielectrics for Nanomagnetic Logic Circuits

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
_r
) of 452, saturation magnetization (M
_s
) of 636 emu/cm
³
and magnetization at 100 Oe (M
_{100 Oe}
) of 398 emu/cm
³
. Effect of low temperature is discussed, and measurements show that the EPD remains superparamagnetic at 173 K; μ
_r
, M
_s
and M
_{100 Oe}
values at reduced temperatures are higher than those at room temperature. The sample is ferromagnetic at 100 K.