Singh H.,Indian Institute of Science |
Gupta R.,Devi Ahilya University |
Chakraborty T.,Indian Institute of Science |
Gupta A.,Indore Center |
Mitra C.,Indian Institute of Science
IEEE Transactions on Magnetics | Year: 2014
We report the unusual and exotic phenomenon of positive exchange bias observed in all ferromagnetic layered soft/hard Fe/Co spring magnet systems. Interestingly, the results are well reproducible both at low (5 K) and room temperatures (300 K). The effect of applied magnetic pinning field of 7 and-5 T reveals a noticeable shift of magnetic hysteresis loops along the field direction. We argue that the reason behind observed positive exchange bias is the establishment of antiferromagnetic (AFM) exchange coupling at the interface as a result of intermixing of Fe into the Co layer. The collective coupling of this intermix layers is AFM which facilitates positive shift of magnetic hysteresis loop. © 2014 IEEE.
Soni S.,Devi Ahilya University |
Nair K.G.M.,Indira Gandhi Center for Atomic Research |
Phase D.M.,Indore Center |
Gupta R.,Devi Ahilya University
AIP Conference Proceedings | Year: 2012
TiN thin films prepared by laser treatment using Kr-F excimer laser in the controlled atmosphere. The depth distribution and composition of nitrogen and contaminated oxygen have been determined by non-Rutherford proton backscattering using 1.7 MeV Tendetron accelerator. The electronic structure of TiN thin film have been characterized by resonant photoelectron spectroscopy using indus-I synchrotron radiation. Specifically, complex resonance profile that shows the enhancement at 45 eV which is consistent with the resonant photoemission of Ti 3d states involved in the Titanium nitride and oxide. © 2012 American Institute of Physics.
Ghosh B.,Jadavpur University |
Kumar S.,Jadavpur University |
Poddar A.,Saha Institute of Nuclear Physics |
Mazumdar C.,Saha Institute of Nuclear Physics |
And 3 more authors.
Journal of Applied Physics | Year: 2010
The effects of particle size, structure, microstrain, and cation distribution on magnetic property of nanosized Ni0.35Zn 0.65Fe2O4 prepared through high-energy ball milling have been explored by a wide variety of experimental technique namely, x-ray diffraction, high-resolution transmission electron microscopy, dc magnetization measurement, and Mössbauer spectroscopy. The sample exhibits mixed magnetic behavior with a collective magnetic state between 300 and 60 K while spin glasslike freezing of magnetic moments has taken place below 60 K. The sample has displayed enhancement in magnetization, magnetic hyperfine field, coercivity, and anisotropy energy. The inherent superparamagnetic relaxation of ferrite nanoparticles has significantly reduced and it shows evidence of magnetic hysterisis at room temperature. These properties could be profitably used to overcome the inherent instability of magnetic nanoparticles. The intersublattice interaction (JAB) in the sample has strengthened due to migration of Fe3+ ions from octahedral (B) site to tetrahedral (A) site and this accounts for the genesis of counterintuitive magnetic enhancement in the sample. © 2010 American Institute of Physics.
Mondal T.,Sikkim University |
Tripathi A.,Sikkim University |
Zhang J.,Xi'an Jiaotong University |
Sathe V.,Indore Center |
And 3 more authors.
Journal of Physical Chemistry C | Year: 2015
We present a Raman spectroscopy investigation of the vibrational properties of a rare-earth endohedral metallofullerene, Gd@C82, at low temperatures. While lowering the temperature, the Raman spectra show a blueshift in the Gd-C and C-C vibrational modes which are attributed to both anharmonic and thermal expansion contributions in the fullerene cage. The experimental data are compared with the theories of the shift and broadening of the phonon lines, and respective anharmonic and temperature coefficients are evaluated. In addition, the force constant of the Gd-C82 vibration is derived at various temperatures using a linear harmonic oscillator model. No change in the oxidation state of the ion is noted in the examined temperature range. (Graph Presented). © 2015 American Chemical Society.
Latthe S.S.,Shivaji University |
Imai H.,Keio University |
Ganesan V.,Indore Center |
Venkateswara Rao A.,Shivaji University
Microporous and Mesoporous Materials | Year: 2010
Wettability of solid surfaces is a crucial concern in our daily life as well as in engineering and science. The present research work describes the room temperature synthesis of adherent and porous superhydrophobic silica films on glass substrates using methyltriethoxysilane (MTES) as hydrophobic reagent by sol-gel process. The coating sol was prepared by keeping the molar ratio of tetraethoxysilane (TEOS), methanol (MeOH), water (H2O) constant at 1:22.09:6.25, respectively, with 0.01 M NH4F catalyst throughout the experiments and the MTES/TEOS molar ratio (M) was varied from 0 to 0.43. The static water contact angle as high as 160° and water sliding angle as low as 3° was obtained for silica film prepared from M = 0.43. The surface morphological study showed the porous structure with pore sizes ranging from 250 to 300 nm. The superhydrophobic silica films retained their superhydrophobicity up to a temperature of 290 °C and above this temperature the films became superhydrophilic. The prepared silica films were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared (FT-IR) spectroscopy, percentage of optical transmission, humidity test and static and dynamic water contact angle measurements. © 2009.