Elastic shear moduli measurements on Fe100-xGax (x=12-33) single crystals (via resonant ultrasound spectroscopy) with and without a magnetic field and within 4-300 K are reported. The pronounced softening of the tetragonal shear modulus c' is concluded to be, based on magnetoelastic coupling, the cause of the second peak in the tetragonal magnetostriction constant X 100 near x=28. Exceedingly high Delta E effects (similar to 25), combined with the extreme softness in c' (c'< 10 GPa), suggest structural changes take place, yet, gradual in nature, as the moduli show a smooth dependence on Ga concentration, temperature, and magnetic field. Shear anisotropy (C-44/c') as high as 14.7 was observed for Fe71.2Ga28.8. (c) 2005 American Institute of Physics.
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机译：报告了Fe100-xGax（x=12-33）单晶（通过共振超声波谱）在有和没有磁场且在4-300 K范围内的弹性剪切模量测量。基于磁弹性耦合，四方剪切模量c'的明显软化是四方磁致伸缩常数X 100在x=28附近出现第二个峰值的原因。极高的 Delta E 效应（类似于 25%），加上 c' （c'< 10 GPa） 的极度柔软度，表明结构发生了变化，但本质上是渐进的，因为模量显示出对 Ga 浓度、温度和磁场的平滑依赖性。Fe71.2Ga28.8的剪切各向异性（C-44/c'）高达14.7。（c） 2005年美国物理研究所。
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