Simultaneous measurement of field dependence of elastic moduli by laser interferometry

A methodology is applied which allows the simultaneous determination of the Youngs modulus and the shear modulus to evaluate elastic moduli variations with the magnetic field ($Delta E$ and $Delta G$). The methodology followed is based on the simultaneous detection of the transverse and torsional natural frequencies of a slender magnetic bar found inside a solenoid. The resultant vibration is detected via a heterodyne interferometric optical system with a broad bandwidth. The detection and excitation systems of the vibration do not interact with the sample. The applicability of the method is shown characterizing 10mm-diameter nickel bars. The results are compared with those obtained from longitudinal vibrations.