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Growth and Studies on Pure and Doped Magnetoelectric GdMnO3 Single Crystals
|Aditya A. Wagh , Anil Kumar P S , Suja E. Saji|
Indian Institute of Science, Bangalore 560 012, India
|Various multiferroic materials classified as “improper ferroelectrics,” are known to posses polar state due to different types of ordering. They exhibit large magneto-electric coupling and are further sub-categorized as geometric, electronic and magnetic ferroelectrics. Divalent doping is known to introduce significant changes in physical properties. Our studies on pure and strontium doped GdMnO3 are discussed here. We have grown single crystals of GdMnO3 and Gd0.5Sr0.5MnO3 using float-zone method. Growth parameters are optimized to yield good quality single crystals. Preliminary characterization is carried out to ensure phase purity, crystallinity and composition. In order to investigate anisotropic properties of these crystals, they are oriented using back-reflection Laue technique and cut into appropriate dimensions for the experimental measurements. Magneto-dielectric and electric polarization measurements are performed in the temperature range, 5 to 100 K at applied magnetic fields ranging from 0 – 50 kOe. GdMnO3 exhibits interesting antiferromagnetic transitions. At ~ 43 K, it transforms to long-wavelength modulated collinear structure, which is incommensurate . At ~ 23 K, an A-type antiferromagnetic phase sets in . Application of magnetic field (10 KOe) along b-axis induces ferroelectric phase along a-axis in GdMnO3 crystal . Tuning of electric polarization with magnetic field and magneto-dielectric effects are studied in this configuration. Specific heat measurements are carried out to probe low temperature magnetic transitions of both crystals. Gd0.5Sr0.5MnO3
shows glass-like magnetic phase below ~ 32 K . It also exhibits interesting features like, charge ordered insulating phase and colossal magnetoresistance [2,3]. Dielectric behaviour is investigated on oriented single crystals. Thermal, magnetic and dielectric properties as well as growth aspects of these gadolinium manganite crystals will be discussed in detail.
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(3) B. Garcia-Landa, J. M. De Terasa and M. R. Ibarra, J. Appl. Phys. 83, 12, 7664(1998).
Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Suja E. Saji
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-15 16:35 Revised: 2013-04-16 19:31