R. J. Choudhary

R. J. Choudhary
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Physics - Materials Science (14)
 
Physics - Strongly Correlated Electrons (10)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (1)
 
Mathematics - Numerical Analysis (1)
 
Physics - Fluid Dynamics (1)

Publications Authored By R. J. Choudhary

We report the magnetoresistance and nonlinear Hall effect studies over a wide temperature range in pulsed laser deposited Ni0.07Zn0.93O thin film. Read More

The effects of MHD boundary layer flow of non-linear thermal radiation with convective heat transfer and non-uniform heat source/sink in presence of thermophortic velocity and chemical reaction investigated in this study. Suitable similarity transformation are used to solve the partial ordinary differential equation of considered governing flow. Runge-Kutta fourth fifth order Fehlberg method with shooting techniques are used to solved non-dimensional governing equations. Read More

This paper proposes method for detection, estimation of Thevenin equivalent parameters to describe power system behavior. Thevenin equivalent estimation is a challenge due to variation in system states caused by power flow in the network. Thevenin equivalent calculation based on changes in system with multiple sources integrated with grid, isolated distributed generator system is analysed and nonlinear least square fit estimation technique for algorithm is adopted. Read More

Models coming from different physical applications are very large in size. Simulation with such systems is expensive so one usually obtains a reduced model (by model reduction) that replicates the input-output behaviour of the original full model. A recently proposed algorithm for model reduction of bilinear dynamical systems, Bilinear Iterative Rational Krylov Algorithm (BIRKA), does so in an optimal way. Read More

Two dimensional (2D) layered materials have recently gained renewed interest due to their exotic electronic properties along with high specific surface area. The prospects of exploiting these properties in sensing, catalysis, energy storage, protective coatings and electrochromism have witnessed a paradigm shift towards the exploration of these sophisticated 2D materials. The exemplary performance of graphene (1) which is among the first of these elemental 2D materials have initiated a runaway effect in the pursuit of studying alternative 2D materials. Read More

We report the existence of ferromagnetic correlations (FMC) in paramagnetic (PM) matrix of cubic La1-xSrxMnO3-{\delta} (x = 0.80, 0.85) well above its coupled structural, magnetic and electronic phase transitions. Read More

Magnetic and dielectric studies of SrCu3Ti4O12 carried out over 5-300K confirm antiferromagnetic (AFM) ordering of Cu-spins at TN =23K. Dielectric constant {\epsilon}' measured across 1Hz-1MHz signifies quantum paraelectric character, Barrett-fittable almost down to TN. Competition of athermal fluctuations and the literature-reported magneto-phonon-softening near TN manifests a maiden quantum paraelectric glass (QPG) state. Read More

Structural phase transition studies employing low-temperature transmission electron microscopy, and low-temperature x-ray diffraction have been carried out on nearly stoichiometric ({\delta}=0.01) and off-stoichiometric ({\delta}=0.12) versions of La0. Read More

The influence of La and Nd co-substitution on the structural and magnetic properties of BiFeO3 (BFO) thin films was examined. Epitaxial thin films of pure and, La and Nd co-doped BFO on the SrRuO3 buffered single crystal SrTiO3 (001) substrate were deposited using pulsed laser deposition. The structural change in co doped La and Nd BFO thin films which was caused by the changes of force constant in the crystal lattice induced by ionic radii mismatch was investigated. Read More

We demonstrate interface energy level engineering, exploiting the modification in energy band structure across Verwey phase transition of $Fe_{3}O_{4}$ electrode, in a $Fe_{3}O_{4}$(111)/$Alq_{3}$/Co vertical spin-valve (SV) device. Experimental results on device characteristics I-V) study exhibit a transition in conduction mode from carrier injection to tunneling across Verwey transition temperature ($T_{V}$) of $Fe_{3}O_{4}$ electrode. Both giant magneto-resistance (GMR) and tunneling MR (TMR) have been observed in a single SV device as a function of temperature, below and above $T_{V}$, respectively. Read More

Thin films of magnetite (Fe3O4) are grown on single crystal GaAs (100) substrate by pulsed laser deposition. X ray diffraction (XRD) result shows the (111) preferred orientation of the Fe3O4 film and x-ray photoelectron spectroscopy confirm the presence of single phase Fe3O4 in the film. The electrical transport property of the film shows the characteristic Verwey transition at 122 K and below 110 K, the transport follows variable range hopping type conduction mechanism. Read More

Thin films of Fe3O4 have been deposited on single crystal MgO (100) and Si (100) substrates using pulsed laser deposition. Films grown on MgO substrate are epitaxial with c-axis orientation whereas, films on Si substrate are highly <111> oriented. Film thicknesses are 150 nm. Read More

We report the growth of undoped and Fe (2 and 5 at. percentage) doped molybdenum oxide thin films on c-plane of sapphire substrate using pulsed laser ablation. X-ray diffraction results show that the films are oriented in (100) direction and have monoclinic structure based on MoO2 phase as also supported by Raman spectroscopy. Read More

The electronic structure of pulsed laser deposited Mo1-xFexO2 (x=0, 0.02 and 0.05) thin films has been investigated using resonant photoemission spectroscopy near Mo-4p absorption edge. Read More

The effect of substrate strain on the electronic valence band structure of La0.7Ca0.3MnO3 thin films has been investigated. Read More

The resistivity and magnetoresistance measurements were carried out on thin film of La0.7Ca0.3MnO3 to investigate the possible origin of low temperature resistivity minimum observed in these samples. Read More

Resonance Raman (RR) peaks of and stretching modes and their higher harmonics have been observed superimposed on photoluminescence (PL) spectrum of thin films. Commercial fluorine doped thin films deposited by sputtering on glass and thin films deposited on Si by laser ablation have been studied. The dispersions of CO and OH stretching RR modes are ~ 600 cm-1/eV and 800 cm-1 respectively. Read More

Ferromagnetism is observed at and above room temperature in pulsed laser deposited epitaxial films of Co-doped Ti-based oxide perovskite (La1-xSrxTiO3-d). The system has the characteristics of an intrinsic diluted magnetic semiconductor (metal) at low concentrations (<~ 2 %), but develops inhomogeneity at higher cobalt concentrations. The films range from being opaque metallic to transparent semiconducting depending on the oxygen pressure during growth and are yet ferromagnetic. Read More

We report on the optical properties of magnetic cobalt-doped anatase phase titanium dioxide Ti_{1-x}Co_{x}O_{2-d} films for low doping concentrations, 0 <= x <= 0.02, in the spectral range 0.2 to 5 eV. Read More