Research

1. ) Phase stability and co-existence of competing phases in magnetic nanowires in context of manganite nanowires

Nanowires, because of their unique one-dimensional like structural characteristics and size effects, exhibit many novel physical properties, that are different from their bulk counterparts. During past two decades much effort has been made to synthesize and characterize 1D nanostructure of manganites in the form of NW, tube, rods etc. The issues related to control of size, shape, structure, composition, homogeneity and growth kinetics of the perovskite oxide manganite NWs are still remained unexplored. In addition to these issues, how the size reduction to one dimension affects (with large aspect ratio structure) the crystallographic, magnetic, transport and other physical properties of NWs of manganite compared to bulk has been less investigated. In this work, we mainly focus on these issues and the underlying physics behind this .

2.) Physics and Technology with single nanowire devices Single NW devices:

Nano-fabrication The lithographic facilities in the clean room was used for optical lithography, electron beam lithography (EBL) and focused ion beam (FIB) lithography to integrate sub- 100nm nanowire of materials produced by bottom-up approach like chemical route or physical/chemical vapour deposition to a single nanowire device connected to 2 or 4 probes. For attaching nanowires to prefabricated contact pads for optoelectronic or electronic measurements in addition to EBL –lift off, FIB or Focused electron beam deposited metals (Pt or W) are also used. Finally transport measurement on Single Nanowire was done.

3.) Nucleation site and interface controlled growth of complex and binary oxide nanowires and nanotubes by solvo-thermal and Pulsed Laser Deposition.

This work provides information about synthesis and physical property study of metal binary oxide nanostructures (e.g WO3, TiO2). Binary (metal) oxide nanostructure created much more attention in last 4-5 decades due to its versatile nanostructure and different synthesis techniques, which may able to control/modify its physical properties. The main motivation of this thesis work involve growth of vertically aligned 6 nanowires in physical vapour deposition technique (like, Pulse Laser Deposition (PLD) technique), which is a non trivial technique for growth of 1D kind structure. Moreover, it also involves the growth of nanorods/nanoflowers kind structure in laser assisted wet chemistry technique and porous 1D nanostructures by hydrothermal (wet chemistry) method by tuning the growth parameters and techniques. Further, the physics behind the growth of these nanostructures has been investigated by cross sectional interface physics study which involves spatially resolved tools for sample preparation and microstructural analysis in details.

4) Synthesis , Physical Properties & Applications of Halide Perovskites

Since last several years I have stared working on halide perovskites also where our main focus is to study different physical properties (like optoelectronic , radiation detection and gas sensing etc) of this system by growing good quality samples starting from single crystal, thin films, nanocrystals etc. The as prepared samples are used to fabricate devices using different tools like lithographic , interdigitated electrode pattering, to form photo detector, solid state gas sensor as well as based radiation detector, photo FET by them. In recent days, we are also trying to explored structural, dielectric, transport properties to get better insight structure property correlation of these kinds of compounds through techniques like Synchrotron XRD, Impedance Spectroscopy and Low temperature Resistivity measurements as well as Raman Spectroscopy.