Magnetocaloric and phase coexistence in La0.5Ca0.5–xSrxMnO3 manganites

Abstract

Structural, magnetic, and magnetocaloric properties of the phase separated La0.5Ca0.5–xSrxMnO3 (x = 0, 0.2, 0.3, 0.4, and 0.5) manganites have been studied. The results show that the phase coexistence state can be investigated by magnetocaloric studies (especially the field dependence of magnetic entropy change at constant temperature). Magnetic entropy change (△SM) shows positive (negative) peak at the vicinity of TN (TC). However, in the intermediate temperatures between TN and TC, both the sign and magnitude of △SM are strongly dependent on temperature and magnetic field, manifesting the competition of ferromagnetic (FM) (negative △SM) and non-FM (positive △SM) phases. This behavior is more pronounced in the parent compound, La0.5Ca0.5MnO3, in which the intermediate phase separation ranges between 160 and 225 K. The substitution of Ca by Sr enhances the ferromagnetic state, weakens the phase separation, and thus narrows the temperature range in which the field related effects (such as the sign change of △SM) are observed.

Thermal cycling memory in phase separated manganites

“…Phase separated manganites [1], have been the focus of extensive research during the last 15 years due to the high interplay between their electric, magnetic and structural degrees of freedom. That interplay gives rise to a wide variety of physical properties with many potential technological applications, as for example the colossal magnetoresistance effect (CMR) [1], the nonvolatile memory effect (NVM) [2,3], the magnetocaloric effect (MCE) [4,5,6], a resistive switching effect (RS) induced by the application of an electric potential [7,8,9], etc. The phase separated state of manganites is characterized by the coexistence of different magnetic phases and is the key to understand those phenomena.…”

Size induced magnetic phases in half doped manganite nanowires of La0.5Sr0.5MnO3: a neutron diffraction study

“…In recent years, the phase coexistence state of manganites has been investigated by magneto-caloric studies, i.e. using the magnetic entropy change (ΔS M ) [17,26,[41][42][43].…”