In situ TEM observation of thermally-induced first-order magnetic transition in itinerant-electron metamagnetic La(Fe xSi 1-x) 13 compounds

Abstract

Defocus mode of Lorentz microscopy has revealed change in the magnetic microstructure with a first-order magnetic phase transition in La(Fe xSi 1-x) 13 compounds (0.86 ≤ x. ≤ 0.90). Upon heating specimens from the ferromagnetic phase to the paramagnetic phase, magnetic domains disappear instantaneously at the Curie temperature, concurrent with a substantial change in the volume. The observations are consistent with the feature of the first-order phase transition, which gives rise to extraordinary phenomena of these compounds such as large magnetocaloric effects. © 2005 The Japan Institute of Metals.