Department of Physics

Research Topics of Study and Grants

Studies on similarities and differences in the characteristics of stochastic and vibrational resonances are identified. Vibrational resonance is shown to occur only in the presence of hysteresis. Shape of the signal is found to alter the characteristics of stochastic resonance. Stability boundaries of periodic orbits and resonance dynamics are studied analytically in a two coupled Duffing - van der Pol oscillators. Analytical and numerical analysis on homoclinic bifurcations in asymmetrical Duffing oscillator are being carried out.

Analysis of spatiotemporal patterns and chaos synchronization in certain arrays of coupled dynamical systems is carried out. In particular, investigations on the nature of synchronizing transitions and size dependence in arrays of diffusively coupled dynamical systems are going on. Low dimensional behaviour and finite time predictability of coupled map lattices and arrays of diffusively coupled nonlinear oscillators are under detailed investigation. Studies on various properties in the context of chaos, different synchronization scenario in time delay systems have also been undertaken. <

Algorithms and efficient computer codes based on split-step Crank-Nicholson and pseudospectral methods are developed for solving partial differential equations in one-, two- and three dimensions. In particular, investigations are being made on various aspects of Bose-Einstein condensates such as the effect of periodic modulation, formation of vortex lattices, bright and dark solitons and their interactions, influence of optical lattice potential, and dipolar interactions by numerically solving the corresponding nonlinear Gross-Pitaevskii (GP)/Nonlinear Schrdinger (NLS) equations in one-, two- and three-dimensions.

Data analysis on the daily temperature variations using various nonlinear time series analysis and statistical tools is carried out. Also investigations on agent-based models (eg. minority game model) in financial markets have been carried out.

The main objective of our research group is to grow high quality and technologically important single crystals and thin films. Important crystal growth techniques including Czochralski, Bridgman, Vertical dynamic gradient freeze, top seeded solution growth and low temperature solution growth have been developed to grow single crystals of organic, inorganic and semi-organic materials for nonlinear optical, piezoelectric and scintillator applications. Thin film deposition techniques including spray pyrolysis, spin coating and chemical bath deposition have been established for preparing thin films of transparent conducting oxide, organic-fullerene, metal-organic, perovskite materials for opto-electronic, solar cell, gas sensors and thermo-optical applications. Further, CGTF lab involves on the preparation of nanomaterials and nanocomposites for magnetic, ferroelectric, biological applications.

•  Some technologically sound materials developed in the CGTF lab
• Single crystals for nonlinear optical applications
• L-Lysine, L-arginine and L-proline based semi-organic materials using unidirectional solution growth method
• Benzimidazole, Aminobenzophenone and 8-hydroxyquinoline by vertical Bridgman and vertical dynamic gradient freeze methods
• Alkali metal and Melilite type borate materials by Czochralski method
• Potassium niobate by top seeded solution growth method
• Thin films for opto-electronic, solar cells, gas sensing and thermo-optical applications
• Rare earth and transition metal ions doped CdO, SnO₂ and CoFe₂O₄ thinfilms by Spray pyrolysis
• Cd₂SnO₄, Cu_0.87Se, CuTe, GaTe and Cu₄Bi₄S₉ thin films by electron beam evaporation
• Benzimidazole based metal-organic complexes by chemical bath deposition technique
• Nanomaterials for magnetic and ferroelectric applications
• Metal-ions substituted, surfactant and polymer assisted CoFe₂O₄, KNbO₃ nanoparticles and nanocomposites by co-precipitation method
• Benzimidazole based metal-organic nanoparticles by re-precipitation method

This research group is engaged in the research of understanding light-matter interaction at nanoscale. Research activities are primly focused on the preparation and characterization of multifunctional nanomaterials suitable for photonics applications. The underlying aim is to understand the nanostructured materials: (i) nonlinear optical behavior under high intense laser light interaction and (ii) photovoltaic performance for solar cells. Materials chosen for investigation includes layered structures, borates, niobates and biomolecules that provides rich opportunities to unravel the different aspects of advanced optics such as NLO (Frequency conversion and optical limiting) and semiconductors (photoanodes and photocathodes). Major experiments that are performed in the research group includes: Preparation of organized self-assembled thin films by Langmuir-Blodgett method, Kurtz and Perry powder technique for SHG measurement, Z-scan experiment for investigating nonlinear optical phenomena and laser induced surface damage studies. Fabrication of devices such as frequency converters (for short wavelength laser generation), optical limiters (for laser safety devices) and bio sensitized tandem solar cells (for green energy harvesting) are being under taken. Few noteworthy outcomes of the researche groups include: Enhanced broadband optical limiting in functionalized solar exfoliated reduced graphene oxide- Ag-Fe₂O₃ and Au-Fe₂O₃ nanocomposites, Bacteriorhodopsin sensitized preferentially oriented one dimensional TiO₂ nanorod polymorphs as efficient photoanodes for high-performance bio-sensitized solar cells, Improved production of bacteriorhodopsin from Halobacterium salinarum through direct amino acid supplement in the basal medium, Copper niobate based photocathodes for p-DSSCs and tandem solar cells.

GLOBAL civilization requires inexpensive, reliable, and sustainable energy sources. The energy demands of today's society will continue to grow due to heavy industrialization and growing population in third world countries. Currently, faced with a dwindling supply of fossil fuels and adverse global climate change, the search for a viable source of inexpensive renewable energy is quest of ongoing research. Among the clean energy sources, solar energy is one of the most promising and fastest growing renewable energy sources worldwide, particularly much suitable for countries like India as the mercury scorches 12 Hrs a day. Photovoltaic (PV) cells convert sunlight directly into electricity and offer enormous potential as a source of sustainable energy. A large variety of planar thin films and nanomaterials technologies including nanowire arrays, quantum dot, dye-sensitized, hybrid organic and perovskite solar cells are being actively researched due to their potentially low-cost production and possibility of higher performance than current crystal Si technology. The quest in developing functional materials with wide range of absorption in the visible solar spectrum and enhanced charge separation is vital in achieving high efficient solar cells.

The researchers in our department are focused on the development of sustainable fabrication routes for functional materials, characterize their functional properties and to determine sustainable, cost-effective processing for the fabrication of green energy harvesting devices. The novel green approaches include, Nanowire Solar cell, Dye-sensitized solar cell, Hybrid-organic polymers solar cell, Mesoscopic perovskite solar cells and PEC water splitting for Hydrogen generation.

In order to encourage research in the area of high pressure and low temperature studies, in 2008, the university initiated a Centre for High Pressure Research in the Department of Physics. The Centre investigates experimentally various materials such as manganites, superconductors, diluted manganite semiconductors and organic conductors at extreme conditions like high pressure (3-6GPa), low temperature (2K) and high magnetic field (9Tesla). Correlated electrons with multi-degrees of freedom can host the correlation phenomena. Strong coupling exists between lattice strain and orbital ordering. The Centre has a facility to investigate the interplay of spin, charge and orbital coupling through hydrostatic and uniaxial pressure of various strongly correlated systems at low temperature and high magnetic field. The Centre has developed indigenous high pressure devices for transport measurements.

In view of initiating research in emerging and frontier topics, a Centre for Nanoscience and Nanotechnology has been established in 2008 in the Department of Physics by the University. The mission of the Centre is to promote, develop and binding interdisciplinary research activities in Bharathidasan University. Nano User Facility is created to extend the the state of the art experimental facilities to internal/external and industrial users at nominal cost.

Centre for nanoscience and nanotechnology has diversified its research interest in the following areas, (i) One-dimensional self-assembled nitride semiconductor (GaN, InN, AlN and its alloys, core-shell nanowires) nanostructures for LEDs, Solar cell and water splitting applications, (ii) 2D layered materials (Graphene, MoS₂, WS₂, NbS₂, etc), (iii) Hybrid organic and inorganic Pervoskites for next generation photovoltaic applications, (iv) Photo-electrochemical assisted water splitting and (v) Drug Delivery and SERS detection of bio molecules.

General Grant for Research and Teaching from Agencies

The Department of Physics has completed several research projects in the areas of nonlinear dynamics, biophysics, thin films, crystal growth, nonlinear optical materials, high pressure studies and Nanotechnology funded mainly by DST, UGC, CSIR, DAE, DRDO etc. At present, the following research projects are in progress

Research projects completed during last 5 years (2018-2013)