Patent ID: 8558540

Claim:
A method for measuring a dimensionless coupling constant of a magnetic structure, wherein the magnetic structure comprises, from a bottom layer to a top layer, a substrate, a first metal layer, a RE-TM (Rare Earth-Transition) alloy magnetic layer, a buffer layer and a second metal layer, the method comprising: performing a step of applying an external vertical magnetic field, wherein a temperature of the magnetic structure is reduced to 50K, and the external vertical magnetic field is applied to the RE-TM alloy magnetic layer of the magnetic structure, thereby enabling magnetic moments of the RE-TM alloy magnetic layer to be vertical and saturated; performing a step of measuring a compensation temperature, wherein the external vertical magnetic field is removed, and the compensation temperature is measured when the sum of the magnetization of the RE-TM alloy magnetic layer is zero; performing a step of applying an external parallel magnetic field to the RE-TM alloy magnetic layer; and performing a step of adjusting the temperature of the magnetic structure to the compensation temperature and measuring a hysteresis loop of the magnetic structure under the external parallel magnetic field, wherein an inverse of a slope of the hysteresis loop is a dimensionless coupling constant.