Abhishek Nag

Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9

Abhishek Nag, Srimanta Middey, Sayantika Bhowal, Swarup Panda, Roland Mathieu, J. C. Orain, F. Bert, P. Mendels, P. Freeman, M. Mansson, H. M. Ronnow, M. Telling, P. K. Biswas, D. Sheptyakov, S. D. Kaushik, Vasudeva Siruguri, Carlo Meneghini, D. D. Sarma, Indra Dasgupta, Sugata Ray Email: sspid@iacs.res.in (theoretical), mssr@iacs.res.in (experimental) Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India Centre for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India 3 Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India Department of Engineering Sciences, Uppsala University, P.O. Box 534, SE-751 21 Uppsala, Sweden Laboratoire de Physique des Solides, UMR CNRS 8502, Universit Paris-Sud, 91405 Orsay, France Laboratory for Quantum Magnetism (LQM), École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland Jeremiah Horrocks Institute for Mathematics, Physics & Astrophysics, University of Central Lancashire, Preston PR1 2HE, United Kingdom ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX110QX, United Kingdom Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland UGC-DAE-Consortium for Scientific Research Mumbai Centre, R5 Shed, Bhabha Atomic Research Centre, Mumbai 400085, India Dipartimento di Scienze, Universitá Roma Tre, Via della Vasca Navale, 84 I-00146 Roma, Italy Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India

Magnetic and nonmagnetic tunnel barriers in Sr2FeMoO6

Tunnelling magnetoresistance (TMR) in polycrystalline Sr2FeMoO6 has been a matter of intense interest for more than a decade now, where the nature of the insulating tunnel barrier turned out to be the core issue of debate. Other than the nonmagnetic grain boundaries as conventional tunnel barriers, intragrain magnetic anti-phase boundaries (APB) as well as magnetically frustrated grain surfaces have also been proposed to act as tunnel barriers and influence the TMR response of Sr2FeMoO6 in different ways. In this paper, it is shown that depending upon the physical state of the sample, at least three different types of tunnelling mechanism may persist in polycrystalline Sr2FeMoO6 and a purely conventional TMR response, seldom reported in this important magnetoresistive material, is also possible.

Formation of two-dimensional ordered nanodomains and curious properties of Sr3FeMoO7

Sr3FeMoO7 is a n = 2 Ruddlesden–Popper analogue of the famous double perovskite Sr2FeMoO6 (SFMO), where every two layers of transition metal BO6 (B = Fe, Mo) octahedral planes are interrupted along the c-direction by a SrO layer. Interestingly, these two-dimensional BO6 layers are found to form many highly ordered Fe–O–Mo flat nanodomains separated by antiphase boundaries (APBs) and the interaction between these disc-like ordered domains give rise to interesting magnetic, transport, and magnetotransport properties, such as large magnetoresistance as well as a strong electroresistance.

Giant texturing effect in multiferroic MnWO4 polycrystals

Different methods of texturing polycrystalline materials have been developed over the years to use/probe anisotropic material properties with relative ease, where complicated and expensive single crystal growth processes could be avoided. In this paper, particle morphology assisted texturing in multiferroic MnWO4 has been discussed. Detailed powder x-ray diffraction vis-a-vis scanning electron microscopic studies on differently annealed and processed samples have been employed to probe the giant texturing effect in polycrystalline MnWO4. A quantitative measure of the texturing has been carried out by means of the Rietveld analysis technique. Qualitative presentation of magnetic and dielectric data on textured pellet demonstrated the development of clear anisotropic physical properties in polycrystalline pellets. Finally, we established that the highly anisotropic plate-like particles are formed due to easy cleavage of the significantly large crystalline grains.