Floating zone crystal growth and magnetic properties of bilayer manganites Pr(Sr1−xCax)2Mn2O7

• Published in: Journal of crystal growth 2012-08, Vol.353 (1), p.25-30
• Main Authors: Deng, Guochu, Thiyagarajan, R., Mohan Radheep, D., Pomjakushina, Ekaterina, Medarde, Marisa, Krzton-Maziopa, Anna, Wang, Shuang, Arumugam, S., Conder, Kazimierz
• Format: Article
• Language: English
• Subjects: A2. Floating zone technique; A2. Single crystal growth; B1. Manganites; B2. Magnetic materials; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Crystals; Diffraction; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General studies of phase transitions; Growth from melts; zone melting and refining; Manganites; Materials science; Methods of crystal growth; physics of crystal growth; Orbitals; Order disorder; Order-disorder and statistical mechanics of model systems; Partial pressure; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; X-rays
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.04.024

Single crystals of a bilayer manganite series Pr(Sr1−xCax)2Mn2O7 (x=0, 0.4, 0.9, 1) have been grown using traveling solvent floating zone technique under various oxygen partial pressure. It was found that the crystal quality is very sensitive to oxygen partial pressure applied during growth and highly Ca doped crystals could only be obtained at elevated oxygen pressure. Whereas a secondary phase was observed for PrCa2Mn2O7 grown at oxygen partial pressure below 1bar, a pure phase can be achieved at 8bar of oxygen. This was evidenced studying composition mapping by X-ray fluorescence spectroscopy. X-ray Laue diffraction and X-ray powder diffraction have been carried out on the samples for the quality check of the grown crystals. Susceptibility measurements indicate that all samples are antiferromagnetic at low temperature. They also reveal the existence of two anomalies at ∼320K and 370K, which coincide with the charge ordering/orbital ordering transitions described in the literature. ► Phase-pure multiferroic single crystals of Pr(Sr1−xCax)2Mn2O7 were grown by floating zone method. ► Oxygen pressure was found critical to grow PrCa2Mn2O7 crystal. ► Composition homogeneity by crystal samples show by X-ray fluorescence spectroscopy mapping. ► Two charge/orbital ordering transitions were found in the temperature dependency of susceptibility.