We have designed and fabricated a highly sensitive and accurate torque magnetometer for measuring the magnetic anisotropy of magnetic materials. This torque magnetometer could measure two ranges of torque-± 5dyne·cm and ± 50 dyne·cm- with a 400 ppm sensitivity of the full-scale range selected, and an accuracy of better than 1%. Typical noise levels were 0.002 dyne·cm and 0.02 dyne·cm in the measurement ranges of ± 5 dyne·cm and ± 50 dyne·cm, respectively.
Because of high sensitivity and accuracy of the current system, magnetic anisotropy measurements can be done without stacking for the samples having small magnetization and/or volumes.
We have developed new techniques to measure the magnetization and coercivity of a uniaxial magnetic material using a torque magnetometer. The magnetization could be measured from the linear dependence at low-field regime in a plot of the torque τ versus the applied field H, where the direction of the applied field was perpendicular to the uniaxial orientation. While, the coercivity could be obtained by taking the value of the applied field where the torque was zero, when the direction of the applied field was (180+δ) degrees from the uniaxial orientation. The techniques were applied to determine the magnetizations and coercivities of several Co/Pd multilayer thin films. The results were confirmed to be similar within a 2-percentage difference to those obtained by a vibrating sample magnetometer.
