Stress dependent magnetostriction in highly magnetostrictive Fe100-xGax, 20<x<30

Saturation magnetostriction measurements along the [100] axis of Fe100-xGax single crystal rods (similar to 25X6 mm diameter) were observed to have a linear dependence on [100] applied compressive stresses for 20<x<30. This is not expected from linear magnetoelastic theory and indeed is negligible for x=19.5. An expansion of the magnetoelastic theory to include third order elastic terms reveals the existence of a term that gives rise to a stress dependent [100] magnetostriction. For x =20.9 and 29.5, the stress T dependencies of the saturation magnetostrictions were found to be 0.136 X 10(-6)T MPa-1 and 0.281 X 10(-6)T MPa-1, respectively. Values of the third order elastic constants, c(3)'s, calculated from these values agree both in sign and magnitude with those obtained from stress dependent measurements of Young's moduli and Poisson's ratios. In sum, we conclude that the Fe100-xGax magnetostriction for 0<x<30 can be attributed to a simple homogenous single domain magnetoelastic mechanism. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3058685]