Structural, magnetic, and magnetocaloric properties of bilayer manganite La1.38Sr1.62Mn2O7. (April 2018)

• Record Type: Journal Article
• Authors: Yang, Yu-E.; Xie, Yunfei; Xu, Lisha; Hu, Dazhi; Ma, Chunlan; Ling, Langsheng; Tong, Wei; Pi, Li; Zhang, Yuheng; Fan, Jiyu
• Is Part Of: Journal of physics and chemistry of solids. Volume 115(2018)
• Page Start: 311
• Page End: 316
• Publication Date: 2018-04
• Subjects: Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2018.01.002
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: In this study, we investigated the structural, magnetic phase transition, and magnetocaloric properties of bilayer perovskite manganite La1.38 Sr1.62 Mn2 O7 based on X-ray diffraction, electron paramagnetic resonance, and temperature-/magnetic field-dependent magnetization measurements. The structural characterization results showed the prepared sample had a tetragonal structure with the space group I 4/ mmm . The Curie temperature was determined as 114 K in the magnetization studies and a second-order paramagnetic-ferromagnetic transition was confirmed by the Arrott plot, which showed that the slopes were positive for all the curves. According to the variation in the electron paramagnetic resonance spectrum, we detected obvious electronic phase separation across a broad temperature range from 220 to 80 K in this magnetic material, thereby indicating that the paramagnetic and ferromagnetic phases coexist above as well as below the Curie temperature. Based on a plot of the isothermal magnetization versus the magnetic applied field, we deduced the maximum magnetic entropy change, which only reached 1.89 J/kg.K under an applied magnetic field of 7.0 T. These theoretical investigations indicated that in addition to the magnetoelastic couplings and electron interaction, electronic phase separation and anisotropic exchange interactions also affect the magnetic entropy changes in this bilayer manganite. Highlights: The structural, magnetic phase transition and magnetocaloric properties of bilayer perovskite manganite La1.38 Sr1.62 Mn2 O7 was studied in details. The PM-FM phase transition observed at Curie temperature 114 K was verified to be a second order of phase transition. The paramagnetic and ferromagnetic phase coexist both above and below the Curie temperature. The deduced magnetic entropy change was understood by the theoretical model.