Author:
Campillo G,Figueroa A I,Arnache O,Osorio J,Marín Ramírez J M,Fallarino L
Abstract
Abstract
In this work we report on the magnetocaloric effect of La2/3Ca1/3MnO3 (LCMO) and La2/3Ca1/3Mn0.94Cr0.06O3 (LCMCrO) manganite thin films grown by DC magnetron sputtering on LaAlO3 (100) substrates. X-ray diffraction shows that both doped and undoped films crystallize in the orthorhombic structure. Magnetic measurements show a decrease in both the Curie temperature, TC
, and the saturation magnetization, MS
, for the LCMCrO sample. The change in the magnetic entropy (ΔSm
) was extracted from hysteresis loops at different temperatures around the ferromagnetic to paramagnetic transition, displaying a maximum of entropy change (ΔSm
)
max
near TC
in both films. Moreover, a shift in (ΔSm
)
max
toward temperatures above TC
with increasing magnetic field and a broadening of the entropy change curve were observed. Results of refrigeration cooling power show a lower efficiency for LCMCrO. In order to obtain a local insight into the magnetic interactions of these films, measurements of X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) were performed. XMCD suggests that an antiferromagnetic coupling between Mn4+ - Mn3+ is favored with Cr3+ incorporation, which reduces the Mn L
2,3 XMCD signal and results in a decrease of MS
and (ΔSm
)
max
in LCMCrO films.
Subject
General Physics and Astronomy