Spontaneous magnetization aboveTCin polycrystallineLa0.7Ca0.3MnO3

Abstract

In the present work, spontaneous magnetization is observed in the inverse magnetic susceptibility of La 0.7 Ca 0.3 MnO 3 and La 0.7 Ba 0.3 MnO 3 compounds above T C up to a temperature T * . From information gathered from neutron diffraction, dilatometry, and high-field magnetization data, we suggest that T * is related to the transition temperature of the low-temperature (high magnetic field) magnetic phase. In the temperature region between T * and T C , the application of a magnetic field drives the system from the high-temperature to low-temperature magnetic phases, the latter possessing a higher magnetization.

A detailed study of the hysteresis in La0.67Ca0.33MnO3

“…1 shows the XRD pattern and Rietveld refinement of the polycrystalline La 0.67 Ca 0.33 MnO 3 . From the Rietveld refinement one may observe the single phase pattern of La 0.67 Ca 0.33 MnO 3 where the unit cell parameters a, b and c were calculated to be 5.47154(7) Å, 5.45690(1) Å and 7.7086(1) Å, respectively, resulting in a unit cell with a volume of 230.162(7) Å 3 , which is in agreement with the literature [4]. Furthermore, Fig.…”

“…Even so, it remains a much debated question whether the material undergoes a FOPT or a SOPT [4,5]. Furthermore, thermal hysteresis has been studied in this material with contradicting results [1,[5][6][7].…”

Quantifying the deleterious role of strong correlations inLa1−xCaxMnO3at the magnetocaloric transition

“…) CMR was attributed to strong electron-phonon coupling arising from the Jahn-Teller (JT) splitting of Mn d levels producing a drastic change of electronic bandwidth at the magnetic transition [17]. Later it was appreciated that percolation due to the existence of ferromagnetic (FM) clusters or phase separated regions up to a temperature T * greater than the ferromagnetic Curie temperature T C [18,19] also played an important role. (Note that the static JT distortion can be calculated from the variation in the Mn-O bond length to the average bond length as defined in Ref.…”

Influence of thermal conductivity on the dynamic response of magnetocaloric materials

“…This material, beyond its complex and fascinating behaviour across the metal-insulator transition (Turcaud et al, 2014), is interesting also for energy conversion applications since recently similar compositions showed promising results when tested in a refrigeration test device with the combination of a modest and reversible MCE and a good mechanical stability (Turcaud et al, 2013)). The Curie temperature of these two systems lies at T C = 258 K.…”