A thermally induced first-order magnetic phase transition in La(Fe 0.90Si0.10)13 has been observed in situ by using Lorentz microscopy in the Fresnel mode. On cooling the specimen, the magnetic domains instantly are formed at the Curie temperature TC as in a fashion of the first-order phase transition. The coexistence of the ferromagnetic and paramagnetic phases was observed at TC, and the phase boundary was confirmed to be located at the grain boundaries. In addition, the observed magnetic domain structure is reproduced without any change even after repeating thermal cycles in the vicinity of TC. This fact strongly implies that the phase transition during thermal cycles does not induce lattice defects which cause serious deterioration.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)