Saritha K Nair | Nanyang Technological University (original) (raw)

Papers by Saritha K Nair

The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure co... more The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO 3 (BFO) and superconducting YBa 2 Cu 3 O 7 (YBCO) grown on a (001) SrTiO 3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

AIP …, Jan 1, 2012

Origin of large dielectric constant in La modified BiFeO3-PbTiO3 multiferroic J. Appl. Phys. 111,... more Origin of large dielectric constant in La modified BiFeO3-PbTiO3 multiferroic J. Appl. Phys. 111, 014113 (2012) Modified Johnson model for ferroelectric lead lanthanum zirconate titanate at very high fields and below Curie temperature Appl. Phys. Lett. 100, 022907 Ultrahigh dielectric constant of thin films obtained by electrostatic force microscopy and artificial neural networks Appl. Phys. Lett. 100, 023101 Size-dependent low-frequency dielectric properties in the BaTiO3/poly(vinylidene fluoride) nanocomposite films Appl. Phys. Lett. 100, 012903 Solute rotation in polar liquids: Microscopic basis for the Stokes-Einstein-Debye model

$Research paper thumbnail of The optical properties of SnO $ _ {2} $ nano-wires by THz time-domain spectroscopy$

Bulletin of the American …, Jan 1, 2011

As feature seizes of devices are reduced below a hundred nanometers and chip frequencies reaches ... more As feature seizes of devices are reduced below a hundred nanometers and chip frequencies reaches high GHz, a convenient method of characterizing thin films in the GHz to THz frequency range has been required. THz time-domain spectroscopy provides a non-destructive, non-...

$Research paper thumbnail of Doping dependence of the electron-phonon and electron-spin fluctuation interactions in the high-$ T_ {c} $ superconductor Bi $ _ {2} $ Sr $ _ {2} $ CaCu $ _ {2} $ O $ …$

Arxiv preprint arXiv: …, Jan 1, 2011

Using ultrafast optical techniques, we detect two types of bosons strongly coupled to electrons i... more Using ultrafast optical techniques, we detect two types of bosons strongly coupled to electrons in the family of Bi2Sr2CaCu2O 8+δ from the underdoped to overdoped regimes. The different doping dependences of the electron-boson coupling strengths enables us to identify them as phonons and spin fluctuations: electron-phonon coupling (λ e−ph ) peaks at optimal doping, and electron-spin fluctuation coupling (λ e−sf ) decreases monotonically with doping. This observation is consistent with two facts: (1) superconductivity is in close proximity with antiferromagnetism at low dopings, and (2) a pronounced lattice renormalization effect at larger dopings.

$Research paper thumbnail of Quasiparticle dynamics in overdoped Bi_ {1.4} Pb_ {0.7} Sr_ {1.9} CaCu_ {2} O_ {8+ δ}: Coexistence of superconducting gap and pseudogap below T_ {c}$

Physical Review B, Jan 1, 2010

Photoexcited quasiparticle relaxation dynamics in overdoped Bi 2 Sr 2 CaCu 2 O 8+δ (T c =65 K, ho... more Photoexcited quasiparticle relaxation dynamics in overdoped Bi 2 Sr 2 CaCu 2 O 8+δ (T c =65 K, hole doping p=0.22) single crystal is investigated as a function of temperature. We provide evidence of a ∼22 meV pseudogap (T * ≈100 K) at this doping level. Our data support the scenario where both the superconducting gap and pseudogap coexist in the superconducting state. Our results also suggest an increased scattering rate between electrons and spin fluctuations as the sample enters the pseudogap phase.

Applied Physics …, Jan 1, 2010

…, Jan 1, 2008

Silver silica nanocomposites were obtained by the sol-gel technique using tetraethyl orthosilicat... more Silver silica nanocomposites were obtained by the sol-gel technique using tetraethyl orthosilicate (TEOS) and silver nitrate (AgNO(3)) as precursors. The silver nitrate concentration was varied for obtaining composites with different nanoparticle sizes. The structural and microstructural properties were determined by x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS) studies were done for determining the chemical states of silver in the silica matrix. For the lowest AgNO(3) concentration, monodispersed and spherical Ag crystallites, with an average diameter of 5 nm, were obtained. Grain growth and an increase in size distribution was observed for higher concentrations. The occurrence of surface plasmon resonance (SPR) bands and their evolution in the size range 5-10 nm is studied. For decreasing nanoparticle size, a redshift and broadening of the plasmon-related absorption peak was observed. The observed redshift and broadening of the SPR band was explained using modified Mie scattering theory.