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 have been induced by controlled pulses of surface acoustic waves (SAW) allowing us 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 observed strong magnetic field dependence correlates 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, following \kappaa>\kappab>\kappac.
Temperature changes of the Fe$_{8}$ molecular magnet during its spin reversal process
Fe $_8$分子磁体中的自旋从亚稳基态到激发态的调谐伴随着这些自旋到全局基态的衰减和晶体温度的增加。我们用两个温度计测量了这个温度，一个强耦合，另一个弱耦合到热浴。我们发现，温度升高到不大于$2.2$ ~K。这一上限与爆燃理论和以前的测量得出的火焰温度一致。鉴于这种温度的增加，我们重新审查的朗道，齐纳和Stuckelberg（LZS）理论的自旋隧道大铁$_8$晶体。
General expressions for the dispersion relation of acoustic radial (breathing) modes in cylinders and cylindrical shells of general anisotropic crystals
