Experimental evidence of the anisotropy of the magnetic deflagration associated with the low-temperature first-order antiferromagnetic (AFM) → ferromagnetic (FM) phase transition in single crystals of Gd5Ge4 is reported. The deflagrations were induced by controlled pulses of surface acoustic waves (SAW) allowing to explore both the magnetic field and temperature dependencies on the characteristic times of the phenomenon. The study was done using samples with different geometries and configurations between the SAW pulses and the direction of the applied magnetic field with respect to the three main crystallographic directions of the samples. The effect of temperature is nearly negligible, whereas a strong magnetic field dependence is observed to correlate with the magnetic anisotropy of the sample. Finally, the role of the SAW pulses in both the ignition and formation of the deflagration front was also studied, and we show that the thermal diffusivity of Gd5Ge4 must be anisotropic.
Available at: http://works.bepress.com/d_l_schlagel/48/