🌐 Cross-Disciplinary Integration
The research domain synergizes expertise across:
· Condensed matter physics (electronic structure, spin interactions)
· Materials chemistry (dopant incorporation, defect control)
· Photonics and optoelectronics (light-matter interaction, photonic design)
· Biomedical engineering (plasmonic biosensors, spectroscopic diagnostics)
· Nanotechnology (bottom-up synthesis, nanocomposite integration)
🔬 Research Overview
The Department's research activities are intricately woven around the design, synthesis, and functional characterization of knowledge-based materials and optoelectronic structures, guided by application-driven objectives. The program operates at the intersection of materials science, solid-state physics, photonics, and spintronics, with an emphasis on multi- and cross-disciplinary integration. A critical thrust is directed toward the convergence of optical and spin degrees of freedom in solid-state platforms—culminating in the advancement of optospintronics.
The core research is segmented into two major axes: Materials Development and Process and Characterization Techniques, each supported by synergistic interaction among chemical synthesis, thin-film growth, photonic structuring, and nanoscale engineering.
🧪 Advanced Functional Materials
1. Heusler and Half-Heusler Compounds
These intermetallic compounds, particularly of the general form X₂YZ (full Heusler) and XYZ (half-Heusler), exhibit tunable electronic band structures, high spin polarization, and topological properties. The research focuses on:
· Ferromagnetic and half-metallic behavior for spin-injection applications
· Tailoring the Fermi surface via elemental substitution, such as Co₂Mn(Si, Ge, Sn), NiMnSb
· Exploring pseudo-ternary compositions (e.g., Co₂MnX₁₋ₓYₓ) for multifunctional integration in spintronic devices
2. Diluted Magnetic Semiconductors (DMS)
The incorporation of magnetic dopants into semiconducting matrices enables carrier-mediated ferromagnetism. Particular interest lies in Co-based DMS systems, for their enhanced Curie temperatures and compatibility with III–V/II–VI semiconductors.
3. Phosphate Glasses Doped with Functional Ions
Phosphate-based vitreous matrices are synthesized with strategically embedded dopants such as:
· II–VI semiconductor nanocrystals (e.g., ZnS, CdSe) for quantum confinement effects
· 3d transition metals (e.g., Cr³⁺, Mn²⁺) introducing luminescent and magnetic properties
· Rare-earth ions (e.g., Nd³⁺, Er³⁺, Eu³⁺) for applications in solid-state lasers, amplifiers, and optical sensors
These are fabricated both in bulk and thin-film formats, enabling application versatility from passive waveguides to active photonic layers.
4. Nanoengineered Metal–Organic Complexes
Rare-earth metal-organic complexes, synthesized at nano- and micro-scales, are embedded in polymer matrices to yield hybrid photonic-functional composites. These systems are tailored for:
· Energy transfer studies
· Flexible optoelectronic devices
· Electroluminescent displays
5. Amorphous and Crystalline GaN Thin Films
GaN-based photonic materials are studied in both amorphous and epitaxial crystalline forms, serving as:
· Active layers in UV optoelectronics
· Templates for multi-quantum well heterostructures
· Platforms for polariton-based photonic devices
6. Multilayer Photonic Heterostructures
The group engineers quasi-periodic dielectric stacks, particularly of the type:
· (SiOₓ + P₂O₅)/ITO/(SiOₓ + P₂O₅)/ITO
These are optimized for photonic bandgap engineering, plasmon-enhanced transmission, and angular-resolved spectral control.
7. Ceramic/Polymer Nanocomposites
Hybrid ceramic–polymer systems are developed for next-generation data storage and logic architectures, leveraging:
· Dielectric tunability
· Electro-optic response modulation
· Mechanical flexibility in integrated photonic circuits
8. Plasmonic Nanoarchitectures for Biomedical Applications
Using noble metal nanostructures (e.g., Au, Ag), the research constructs plasmonic platforms exhibiting localized surface plasmon resonances (LSPR). These structures facilitate:
· Label-free biosensing
· Surface-enhanced Raman spectroscopy (SERS)
· Photothermal cancer therapies
9. Carbon based functionalized materials
Development of new functionalized carbon-based materials starting from graphene, carbon nanotubes, fullerenes which can be used in:
· Sensor’s development;
· Transparent electrodes for solar cells;
· Energy storage and gas detection;
· Composites and coatings;
⚙️ Processing Techniques
A. Bulk Synthesis Methods
• Traveling Solvent Method (TSM)
A solution-mediated crystal growth technique, enabling stoichiometrically controlled growth of bulk Heusler and half-Heusler crystals, particularly where high purity and phase selectivity are critical.
• Traveling Heater Method (THM)
Utilizes a moving heat source to create a localized molten zone in the precursor material, facilitating directional solidification and large-grain growth for magnetic and thermoelectric materials.
• Vertical Gradient Freeze (VGF)
A controlled thermal gradient method for growing large-volume single crystals with minimized dislocation densities. Ideal for complex multi-component systems like Co₂-based Heuslers.
• Wet Synthesis of Phosphate Glasses
Precursor solutions undergo controlled hydrolysis and polycondensation, followed by melt quenching. This low-cost method allows fine control over doping homogeneity and optical transparency.
B. Thin Film Deposition Techniques
• Sol-Gel Processing
A bottom-up chemical route involving hydrolysis of metal alkoxides or chlorides to form oxide networks. Suitable for creating amorphous and crystalline thin films on various substrates.
• Pulsed Laser Deposition (PLD)
Employs high-energy laser ablation of a solid target to deposit films with stoichiometric fidelity, particularly effective for multi-component oxide systems and nitride thin films (e.g., GaN).
• Spin Coating
A high-speed rotational method to deposit uniform thin films from liquid precursors. Widely used for depositing sol-gel-derived layers and polymeric functional coatings.
C. Electrochemical synthesis
· Organic Synthesis: Generating reactive intermediates that are difficult to isolate or using them for complex molecule synthesis.
· Nanoparticle Synthesis: Producing nanoparticles like silver nanoparticles by reducing metal ions in a solvent.
· Metal Deposition: Depositing metals on surfaces for various applications.
🧪 Characterization Techniques
Magnetic and Spin Properties
· Magneto-Optical Kerr Effect (MOKE): Probes surface magnetization through polarization rotation of reflected light, offering insight into spin alignment and domain structure in thin films.
Thermal and Transport Measurements
· Charge and Heat Transport Analysis: Employs Seebeck coefficient, Hall effect, and four-point probe techniques to extract carrier concentration, mobility, and thermal conductivity parameters essential for spintronic and thermoelectric applications.
Spectroscopic and Structural Characterization
· Fourier Transform Infrared Spectroscopy (FTIR): Determines chemical bonding, glass network structure, and vibrational modes in doped glasses.
· UV-VIS-NIR Spectroscopy: Assesses optical bandgaps, absorption coefficients, and transmission properties across electronic transitions.
· Fluorescence Spectroscopy: Maps radiative transitions, excited-state lifetimes, and quantum yields in rare-earth- and transition-metal-doped systems.
· Raman Spectroscopy: Probes phonon modes, structural disorder, and strain effects in crystalline and amorphous materials. A specialized research focus is the development of Raman-based techniques for non-invasive medical diagnostics and in-vivo treatment monitoring.
· RHEED (Reflection High-Energy Electron Diffraction): In-situ monitoring of epitaxial thin-film growth, allowing real-time feedback on surface crystallinity and lattice reconstruction.
Electrical Characterization
· I–V and C–V Profiling: Assess diode behavior, interface states, and carrier injection efficiency
· Impedance Spectroscopy: Probes dielectric relaxation and charge transport dynamics
· Capacitance–Voltage (C–V) and Deep-Level Transient Spectroscopy (DLTS): Interface quality and trap state analysis
· Four-Point Probe Method: Sheet resistance and conductivity measurements of thin films
· Hall Effect Measurements: Carrier type, concentration, and mobility for semiconductors and spintronic materials
Electrochemical characterization
· Cyclic Voltammetry (CV): study redox reactions and determine the electrochemical behavior of materials.
· Electrochemical Impedance Spectroscopy (EIS): Provides information about the impedance of the electrochemical system, which can be used to determine properties like diffusion coefficients and reaction rates.
· Potentiometry: Measures the potential difference between electrodes to determine analyte concentration or activity.
· Amperometry: Measures the current flow at a fixed potential, often used to study reaction kinetics.
· Chronopotentiometry: Measures the potential change at a constant current.
· Chronoamperometry and Chronocoulometry: Measure current or charge as a function of time after a potential step.
