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SPS is organising a seminar by Shiv J. Singh

SPS is organising a seminar by Shiv J. Singh

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SPS is organising a seminar by Shiv J. Singh
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Physics Seminar of the School of Physical Sciences
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Title: Critical current density and vortex phase diagram for new layered high-temperature superconductors CaKFe4As4 (1144)
 

Speaker: Shiv J. Singh

(University of Oxford, Oxford)

 

Date:  October 25, 2017 (Wednesday)

Time: 16:00 hrs (4:00 pm)

Venue: Seminar Room, First Floor, School of Physical Sciences (SPS), JNU

Abstract: Iron-based superconductors have huge potential for high magnetic field applications possessing to their ultrahigh upper critical field (Hc2) and very small anisotropy. Single crystals and thin films studies have proved that the capacities of this new superconductors are high enough for designing superconducting materials for high field generation. In this talk, characteristics and potentials of iron-based superconductors are discussed from various viewpoints in an effort to understand the current status and future prospects. Currently, we are focusing on new family “1144” of iron based superconductors and have performed the magnetic measurements on high quality single crystal and polycrystal of CaKFe4As4 (1144) below the transition temperature, Tc ~ 35 K in the presence of applied magnetic field up to 16 T for out-plane (H//c) and in-plane (H//ab) directions and studied the superconducting properties and vortex dynamics behaviour of this new family. The single crystal exhibits a second magnetization peak (SMP) in the magnetic hysteresis loop only with H//c. The obtained Jc have extremely high value at low temperature that is almost magnetic field independent up to 15 T and are more than 100 times higher than that of any other iron based superconductors such as (Ba,K)Fe2As2 (122), Fe(Se,Te) (11), LiFeAs (1111), SmFeAs(O,F) (1111) and also MgB2, Nb3Sn, NbTi. The flux pinning force density (FP) has been obtained from the Jc-H isotherms at different temperatures and are scaled using the Dew-Hughes’s model to underline the pinning mechanism. The obtained pinning parameters suggest the existence of surface and point core pinning of the normal centres of core interaction. We have constructed the vortex phase diagram for this new 1144 family by comparing with other families of iron based superconductors. The obtained Jc phase diagram for this new family will also be discussed with iron based superconductors and MgB2. Our study depicts that this new family (1144) have high enough to be interesting for magnetic application in all iron based superconductors.

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.