JNU | RTI | Directory | Contact Us | Emergency Services | List of Holidays
-A A +A

Origin of Multiferroicity in the Hexagonal Manganite and Ferrite Systems

Origin of Multiferroicity in the Hexagonal Manganite and Ferrite Systems

Event End Date
Event Title
Origin of Multiferroicity in the Hexagonal Manganite and Ferrite Systems
Event Details
<strong>Seminar of the School of Physical Sciences</strong> <strong>Origin of Multiferroicity in the Hexagonal Manganite and Ferrite Systems</strong> <strong>Hena Das</strong> (University of California, Berkeley) Date: <strong>November 22, 2016</strong> <strong>Abstract:</strong> In recent years Transitional Metal Oxides (TMOs) have captivated the imagination of the researchers in the field of Material Science because of their tremendous utilitarian worth for the next generation energy and information technologies. This class of materials displays a fascinating range of phenomenon which includes ferromagnetism, ferroelectricity, colossal magneto-resistivity, high temperature superconductivity, magneto optics etc. The key to the discovery of what other interesting properties these materials exhibit and in how many more ways their potential can be harnessed in device applications lies in the development of microscopic understanding of structural, magnetic and electronic properties of known materials. Here I will discuss the origin of room temperature multiferroicity in hexagonal manganite and ferrite systems, as revealed in course of my research through first-principles approach. We explained the non-trivial origin of magneto electric (ME) coupling in hexagonal manganite and ferrite systems using a combination of theoretical tools like Density Functional Theory (DFT) based first-principles electronic structure methods, group theoretic techniques and microscopic models [1,2]. Our researches showed how a non-polar trimer lattice distortion not only induced a polarization but also a net magnetization and bulk ME coupling. We were led to propose that this induced polarization, net magnetization and bulk ME coupling, in turn led to the existence of a bulk linear ME vortex domain structure or a bulk ME coupling such that if the direction of the polarization was reversed so did the direction of magnetization. Our recent findings showed that how these improper ferroelectrics could be used to construct room temperature multiferroic superlattices with strong magnetization and ME coupling [3]. It was revealed to us that the same trimer lattice distortion enhanced magnetic transition temperature by reducing the geometric frustration at the triangular ferrite layer, which directed a wide compositional space to find new room temperature magnetoelectric multiferroic hexagonal TMOs. [1] Hena Das, Aleksander L. Wysocki, Yanan Geng, Weida Wu and Craig J Fennie, Nature Communications 5, 2998 (2014). [2] Yanan Geng, Hena Das, Aleksander L. Wysocki, N. Lee, Y.J. Choi, S-W. Cheong, M. Mostovoy, Craig J. Fennie, and Weida Wu, Nature Materials 13, 163-167 (2014). [3] Julia A. Mundy, Charles M. Brooks, Megan E. Holtz, Jarrett A. Moyer, Hena Das, Alejandro F. Rebola, James D. Clarkson, John T. Heron, Steven M. Disseler, Rainer Held, Robert Hovden, Elliot Padgett, Qingyun Mao, Hanjong Paik, Rajiv Misra, Lena F. Kourkoutis, Julie A. Borchers, William D. Ratcliff, Ramamoorthy Ramesh, Craig J. Fennie, Peter Schiffer, David A. Muller and Darrell G. Schlom, Accepted in Nature (2016).  

A warm welcome to the modified and updated website of the Centre for East Asian Studies. The East Asian region has been at the forefront of several path-breaking changes since 1970s beginning with the redefining the development architecture with its State-led development model besides emerging as a major region in the global politics and a key hub of the sophisticated technologies. The Centre is one of the thirteen Centres of the School of International Studies, Jawaharlal Nehru University, New Delhi that provides a holistic understanding of the region.

Initially, established as a Centre for Chinese and Japanese Studies, it subsequently grew to include Korean Studies as well. At present there are eight faculty members in the Centre. Several distinguished faculty who have now retired include the late Prof. Gargi Dutt, Prof. P.A.N. Murthy, Prof. G.P. Deshpande, Dr. Nranarayan Das, Prof. R.R. Krishnan and Prof. K.V. Kesavan. Besides, Dr. Madhu Bhalla served at the Centre in Chinese Studies Programme during 1994-2006. In addition, Ms. Kamlesh Jain and Dr. M. M. Kunju served the Centre as the Documentation Officers in Chinese and Japanese Studies respectively.

The academic curriculum covers both modern and contemporary facets of East Asia as each scholar specializes in an area of his/her interest in the region. The integrated course involves two semesters of classes at the M. Phil programme and a dissertation for the M. Phil and a thesis for Ph. D programme respectively. The central objective is to impart an interdisciplinary knowledge and understanding of history, foreign policy, government and politics, society and culture and political economy of the respective areas. Students can explore new and emerging themes such as East Asian regionalism, the evolving East Asian Community, the rise of China, resurgence of Japan and the prospects for reunification of the Korean peninsula. Additionally, the Centre lays great emphasis on the building of language skills. The background of scholars includes mostly from the social science disciplines; History, Political Science, Economics, Sociology, International Relations and language.

Several students of the centre have been recipients of prestigious research fellowships awarded by Japan Foundation, Mombusho (Ministry of Education, Government of Japan), Saburo Okita Memorial Fellowship, Nippon Foundation, Korea Foundation, Nehru Memorial Fellowship, and Fellowship from the Chinese and Taiwanese Governments. Besides, students from Japan receive fellowship from the Indian Council of Cultural Relations.