Journal or Book Title
Journal of Applied Physics
The magnetic-martensitic phase transformation of Gd5(SixGe1−x)4 (x≈0.5), which occurs close to room temperature, has been observed for the first time using a magnetic force microscope (MFM) equipped with a heating–cooling stage. MFM images obtained from a polycrystalline Gd5(Si2.09Ge1.91) sample and single crystal Gd5(Si1.95Ge2.05)and Gd5(Si2Ge2) samples showed transition to a domain structure at low temperatures indicative of a ferromagnetic phase. Some samples exhibited complex domain structures,suggesting that Gd5(SixGe1−x)4 (x≈0.5) has a strong magnetic anisotropy. As the sample temperature increased the domain structure diminished, reflecting the transformation from ferromagnetic to paramagnetic state. On cooling the sample the domain structurereappeared, but at a lower transformation temperature than on heating. This magnetic phase transformation is highly unusual because it is an “order–disorder” phase transition, which is normally second order, but in this case the “order–disorder” (ferromagnetic to paramagnetic)transition exhibits hysteresis in temperature, indicating that it is first order. Such thermalhysteresis in phase transformation was also observed in thermal expansion experiments. The transformation temperatures obtained in the MFM study are in good agreement with those determined from thermal expansion data.
Copyright 2002 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
American Institute of Physics
Leib, J. S.; Snyder, John E.; Lo, Chester C.H.; Paulsen, Jason A.; Xi, P.; and Jiles, David C., "Magnetic force microscopy characterization of a first-order transition: Magnetic-martensitic phase transformation in Gd5(SixGe1−x)4" (2002). Materials Science and Engineering Publications. 106.