Thermo-Mechanical Properties of Terfenol-D Thin Films
- PDF / 893,063 Bytes
- 5 Pages / 414.72 x 648 pts Page_size
- 30 Downloads / 293 Views
195 Mat. Res. Soc. Symp. Proc. Vol. 360 0 1995 Materials Research Society
EXPERIMENT
Magneto Mechanical Measurement System Film Deposition Magnetic Sensor &
A commercially available Kurt J. Lesker
Actuator
Super Sputtering System III was used to deposit films. The system is equipped with 2-
TerfenoI-D
inch RF & DC magnetron sputtering sources.
S' Substrate
The base vacuum ranges between 6.10-8 and 2"10-. and films are routinely deposited under
Electrode
|
Rim
FM Detector
and 10 mTorr Ar pressure with no intentional F77 Electrostatic Driver substrate heating. The substrates used were Si/SiO2 with 200 nm SiO 2 serving as a Fig. 1: Schematic of the magneto-mechanical diffusion barrier. The deposition rate was 0.2 measurement system. nm/sec for all Terfenol-D films. The deposition source voltage is adjusted to between 250V and 280 V and the current varies accordingly in the range between 150 mA to 250 mA. At such conditions no additional effort is needed to maintain the target alloy composition. Rutherford backscattering (RBS) measurements indicate the same compositions in the film as compared to the alloy target used to deposit them. Terfenol-D so deposited at room temperature is amorphous.
Dynamic Magneto-Mechanical Characterization A special design for magneto-mechanical characterization making use of the high mechanical Q of the film/substrate composite and based on previous designs 7 is shown in fig. 1. The sample and electrode comprise the capacitor of a frequency modulation detector. The same electrode is also used to excite vibrations of the film/substrate composite cantilever electrostatically. The upper part is a magnetic driving and sensing device. The system provides parameters such as the damping (internal friction) and modulus defect of the film/substrate composite which can be deconvoluted into intrinsic properties of the films 8. It is able to excite the composite vibration both electrostatically and magnetically. In the case of magnetic excitation the cantilever deflection is proportional to the interaction force between the cantilever and the field generated by a solenoid magnet above the film. Due to the inhomogeneity of the magnetic field as well as the undefined domain structure in the film, it is impossible to extract absolute quantitative values of the magnetization from the measurements. The data is therefore normalized to the deflection at the lowest temperature and specified as the relative magnetization. In the following figures this relative magnetization is used. The static stress in the film/substrate composite was determined using a cantilever deflection method. Standard devonvolution procedures were used to obtain the stress in the film itself. The domain structure in the deposited Terfenol-D films was recorded by a Digital Nanoscope III atomic force microscope operating in the frequency measurement mode.
196
Thermo-Mechanical Properties of TerfenolD Film The results of a combination of dynamical measurements on a Terfenol-D film grown on a Si/SiO 2 substrate are shown
Data Loading...
