Ultrathin Metals and Graphene based Nanocomposites : Electrical Transport and Magnetism: (@IACS, India)

Research interest: Transport and magnetism in Two dimensional systems and Nanocomposites of them
Materials: Transition Metals, and their Oxides, Graphene, Functionalized Graphene
Details:
Chemical synthesis, solid-state reaction or high energy ball milling was used to synthesize the materials. These were characterized by various standard characterization techniques.
Magnetic measurements of ultra-thin nickel nanosheets showed high magnetic anisotropy and coercive field in comparison to its bulk form.
Addressed an open question on the nature of the magnetic ground state of manganese where our magnetic experiments suggest that manganese is ferromagnetic in the low dimension.
Designed experimental set up to measure magnetodielectric effect at room temperature.
Nickel nanosheets/ Na-4 mica composite and graphene/PVA nanocomposite showed a magnetodielectric effect originating from the movement of interfacial space charge under the magnetic field.
Phenomenal activated transport properties, from hopping to fluctuation induced tunneling, was observed in polymer-based graphene nanocomposites.
Phonon modes in silicate glass were observed to influence the electronic transport in graphene/glass nanocomposite and the resistivity increases non-linearly with temperature.
Developed a technique to create graphene from graphene oxide using high-energy ball milling.

Superconductor - Insulator Transition : Magnetotransport at ultra low Temperature: (@Weizmann Institute, Israel)

Research interest: Superconductor--Insulator Transition (SIT) in nanowires and films of disordered superconductor
Material: Amorphous indium oxide (a:InO)
Details:
Fabrication of nanowire/film devices using lithography technique followed by e-beam evaporation.
Magnetotransport experiments in the mK regime by cooling them in He-3 or dilution refrigerator.
Addressed an open question of observance of negative MR near zero field, in sub 100 nm wide wires.
Finite size effect has been observed while approaching the 1D limit by reducing width and the resistance increased with decrease in wire width, in the superconducting side whereas, an opposite trend is seen in the insulating side, which we explained in the light of charge-vortex duality picture of the SIT.
Study of two-dimensional films of a:InO, which show very high resistance (10 G-Ohm) in the magnetic field induced insulating state and showed strong non-linearity in the current -voltage characteristics because of electron-phonon decoupling.

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Research interest: Low temperature Magnetism and Magnetotransport of rare earth tetraboride family of materials.
Material: Thulium tetraboride (\ce{TmB4}) single crystal
Details:
Observation of exotic magnetic ground states including magnetization plateau for \textit{B} along crystal's c axis by low-temperature magnetic measurements.
Low temperature magneto transport measurements in the antiferromagnetic ground state showed anisotropic magnetoresistance.
Observation of quantum linear magnetoresistance (MR) for magnetic field along crystal's c axis.
Tuning the MR from quantum linear to classical quadratic by rotating the direction of the magnetic field.

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Research interest: Tuning light matter interaction of 2D Materials and Hybrids, using external perturbation
Material: Few layered WS2 and MoS2
Details:
Tuning light-matter interaction in WS2-gold nanoparticle hybrids, studied by Raman and PL spectroscopy.
Tuning the Raman spectra of few layered MoS2 by application of in-plane electric field.

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