Effect of Nd substitution on magnetoelectric properties of Sm 2 BaCuO 5
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Ó Indian Academy of Sciences
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Effect of Nd substitution on magnetoelectric properties of Sm2BaCuO5 SWARNAMAYEE MISHRA, PREMAKUMAR YANDA and A SUNDARESAN* School of Advanced Materials, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India *Author for correspondence ([email protected]) MS received 13 January 2020; accepted 9 April 2020 Abstract. We have investigated the magnetic and magnetoelectric properties of solid solutions in the green phase region of the 211-cuprate system Sm2-xNdxBaCuO5 (x = 0.2, 0.4 and 0.6). These compounds crystallize in the centrosymmetric orthorhombic (Pnma) structure. Upon substitution of Nd, the antiferromagnetic ordering temperature of Cu2? ions (TN1 = 24 K) and Sm3?/Nd3? ions (TN2 = 5 K) remain unchanged. Dielectric anomalies appear at TN1 under applied magnetic field, whose magnitude increases with field, and at TN2 = 5 K under zero magnetic field for all three compounds. Applied magnetic fields induce electric polarization at TN1 that vary linearly with magnetic fields. While the polarization decreases below TN2 in x = 0 and 0.2, it is enhanced for the samples with x = 0.4 and 0.6. Interestingly, an additional anomaly is observed in dielectric and electric polarization data at 23 K for the composition x = 0.4 under the magnetic fields. Our study reveals that the substitution of Nd significantly modifies the electrical properties due to changes in the interactions between 4f–3d moments. Keywords.
1.
Inorganic oxides; magnetism; magnetoelectric effect; polarization; 4f–3d coupling.
Introduction
Magnetoelectric effect involves the coupling between magnetism and electric polarization in materials [1–5]. The possibility of tuning the electric polarization (magnetization) by external magnetic (electric) fields open up an alternate perspectives in the basic understanding of the interesting materials for the design of functional devices, such as magnetoelectric memory and sensitive magnetic field sensors by their cross-coupling effects [6–9]. Besides application potential, the fundamental physics of magnetoelectric materials is rich and fascinating. However, materials with simultaneous magnetic and electric order parameters are rare, as a consequence of the conflicting requirements required to stabilize both states concurrently which involves the simultaneous breaking of time and spatial inversion symmetries [4]. Several investigations have been devoted to 211-cuprates of general formula R2BaCuO5 (R = rare-earths) for their interesting magnetic properties arising from f–d coupling [10–12]. These cuprates crystallize in two different structural types, depending upon the size of the rare-earth This article is part of the Topical Collection: SAMat Focus Issue.
cations. For R2BaCuO5 cuprates with R = Sm–Lu including Y, also called green phases, the structure is described by the centrosymmetric orthorhombic symmetry with space group Pnma, showing the existence o
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