[seminar] Seminar na IF-u, 24. studenog 2016. u 15:00 - Dr. Sumanta Chattopadhyay

[Damir Staresinic]

Institut za fiziku, Bijenička cesta 46, 

predavaonica u zgradi Mladen Paić 

četvrtak, 24. studenog 2016., u 15:00 sati 


Spin-charge-lattice coupling in RMn 2 O 5 multiferroics 


Dr. Sumanta Chattopadhyay 





INAC/MEM/Laboratory Magnetism and Neutron Diffraction (MDN),CEA-Grenoble, 38000 Grenoble, France 





Recently, a magnetically frustrated oxide family with general formula RMn 2 O 5 (R = rare earth, Bi, Y) is drawing considerable attention because of its spin order influenced ferroelectricity below ~40 ± 5 K with an extremely large magnetoelectric coupling. In this multiferroic family, the origin of the large magnetoelectric coupling has been thoroughly studied especially for the members having small R 3+ ions. However, the real microscopic origin of the ferroelectricity is still a matter of great debate. In addition, understanding about the influence of the R 3+ ions on the magnetic and electric orders is not clear and further investigations are required to settle this issue. In this context, studies on the RMn 2 O 5 compositions with large R 3+ ions could provide crucial information to elucidate these ambiguous issues. 

In this presentation, the focus will predominantly be on a particular member of the RMn 2 O 5 series viz. NdMn 2 O 5 . The reasons for choosing this particular composition are twofold. It represents an RMn 2 O 5 compound with large R 3+ ion and it lies in between the paraelectric PrMn 2 O 5 and the ferroelectric SmMn 2 O 5 as far as the compositional phase diagram is concerned. With the help of bulk magnetization, heat capacity, electric polarization, X-ray diffraction, and neutron diffraction data, I would like to describe the multiferroic and the structural properties of this interesting compound [1]. Whenever necessary, comparisons among NdMn 2 O 5 and other typical RMn 2 O 5 compositions will be presented to have a broad overview of this exotic multiferroic series. To address the ambiguous issue regarding the true origin of the ferroelectrity in the RMn 2 O 5 family, I would also like to discuss about our recent results of the single crystal X-ray diffraction measurements performed at 300 K on various multiferroic members of this family of compounds. These results clearly reveal that a weak ferroelectric state can be present even at room temperature in the paramagnetic phase of the RMn 2 O 5 oxides and the low temperature ferrolectricity, which is strong, is actually a spin enhanced process [2]. 




[1] S. Chattopadhyay, V. Balédent, F. Damay, A. Gukasov, E. Moshopoulou, P.Auban-Senzier, C. Pasquier, G. André, F. Porcher, E. Elkaim, C. Doubrovsky, M. Greenblatt, and P. Foury-Leylekian, Phys. Rev. B 93, 104406 (2016) . 
[2] V. Balédent, S. Chattopadhyay, P. Fertey, M. B. Lepetit, M. Greenblatt, B. Wanklyn, F. O. Saouma, J. I. Jang, and P. Foury-Leylekian, Phys. Rev. Lett. 114, 117601 (2015) . 







Voditelji seminara IF-a: Nataša Vujičić i Damir Starešinić 





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