https://idr.niser.ac.in/jspui/handle/123456789/24 2026-04-06T20:47:16Z https://idr.niser.ac.in/jspui/handle/123456789/1226 Title: Superconducting and normal state tunnelling in NbN-GdN-NbN junctions Authors: Senapati, Kartikeswar Abstract: Simultaneous occurrence of insulating and ferromagnetic behaviour in GdN makes it an ideal spin filtering material suitably compatible with other transition metal nitrides, such as NbN. Here we present the effect of spin-filtering on the normal state and superconducting state tunnelling current in lithographically patterned Josephson junctions. A large suppression of junction critical current is observed below Tc of NbN, from which we estimate a spin-filtering efficiency of ∼75% in these room temperature grown GdN layers. The temperature dependence ofsuper-current deviates from the usualAmbegaokar-Baratoff relation at low temperatures, roughly scaling with the magnetic coercivity of the GdN barrier. The critical current Fraunhofer pattern shows highly suppressed side lobes and possible signature of a second harmonic Josephson current. In the normal state conductance we observe possible signatures of spin accumulation effect, which leads to a decrease in conductance at low bias voltages. 2013-02-05T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1223 Title: Measurement of nonlinear refractive index in open-aperture Z-scan experiments Authors: Das, Ritwick; Shukla, Mukesh Kumar Abstract: We present an experimental study on measurement of nonlinear refractive index (n 2) of organic liquids when the thermo-optic effects manifest into large nonlinear phase shifts (Δϕ 0) in an open-aperture Z-scan configuration. Although we do not obtain the familiar peak–valley normalized transmittance curve as in the case of closed-aperture Z-scan technique, we use a theoretical model using Gaussian beam decomposition (GD) technique to estimate the value of n 2. Using this recipe, we obtain the nonlinear refractive index n 2 = −(4.90 ± 1.20) × 10−15 cm2/W for toluene (organic solvent) and n 2 = −(10.60 ± 2.10) × 10−15 cm2/W for an organic polymer solution (10−4 M in toluene). By carrying out absorption measurements directly with an unfocussed Gaussian beam, we found nonlinear absorptions β tol = (2.42 ± 0.20) × 10−13 m/W and β poly = (2.79 ± 0.24) × 10−13 m/W which are close to the expected results. 2014-09-28T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1125 Title: Modular forms and related topics in number theory : Kozhikode, India, December 10–14, 2018 Authors: Sahu, Brundaban Abstract: This book collects the papers presented at the Conference on Number Theory, held at the Kerala School of Mathematics, Kozhikode, Kerala, India, from December 10–14, 2018. The conference aimed at bringing the active number theorists and researchers in automorphic forms and allied areas to demonstrate their current research works. This book benefits young research scholars, postdoctoral fellows, and young faculty members working in these areas of research. 2020-11-25T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1034 Title: Proceedings of the XXIV DAE-BRNS high energy physics symposium, Jatni, India Authors: Mohanty, Bedangadas; Swain, Sanjay Kumar; Singh, Ranbir; Kashyap, Varchaswi K. S. Abstract: This book presents proceedings from the XXIV DAE-BRNS High Energy Physics (HEP) Symposium 2020, held at the National Institute of Science Education and Research, Jatni, Odisha, India. The contributions cover a variety of topics in particle physics, astroparticle physics, cosmology and related areas from both experimental and theoretical perspectives, namely (1) Standard Model Physics, (2) Beyond Standard Model Physics, (3) Relativistic Heavy-Ion Physics & QCD, (4) Neutrino Physics, (5) Particle Astrophysics & Cosmology, (6) Detector Development Future Facilities and Experiments, (7) Formal Theory, (8) Societal Applications: Medical Physics, Imaging, etc. 2022-10-06T00:00:00Z