P. Mallick

Publications (14)16.85 Total impact

• Article: Swift heavy ion irradiation induced modification of structure and surface morphology of BiFeO3 thin film

  B.N. Dash, P. Mallick, P. Dash, R. Biswal, Jai Prakash, A. Tripathi, D. Kanjilal, N.C. Mishra
  Bulletin of Materials Science 01/2013; · 0.88 Impact Factor
• Article: Surface modifications of ultra-thin gold films by swift heavy ion irradiation

  P. Dash, P. Mallick, H. Rath, B. N. Dash, A. Tripathi, Jai Prakash, D. K. Avasthi, P. V. Satyam, N. C. Mishra
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  ABSTRACT: Gold films of thickness 10 and 20 nm grown on float glass substrate by thermal evaporation technique were irradiated with 107 MeV Ag8+ and 58 MeV Ni5+ ions at different fluences and characterized by Grazing Incidence X-ray Diffraction (GIXRD) and Atomic Force Microscopy (AFM). The pristine films were continuous and no island structures were found even at these small thicknesses. The surface roughness estimated from AFM data did not show either monotonic increase or decrease with ion fluences. Instead, it increased at low fluences and decreased at high fluences for 20 nm thick film. In the 10 nm film roughness first increased with ion fluence, then decreased and again increased at higher fluences. The pattern of variation, however, was identical for Ni and Ag beams. Both the beams led to the formation of cracks on the film surface at intermediate fluences. The observed ion-irradiation induced thickness dependent topographic modification is explained by the spatial confinement of the energy deposited by ions in the reduced dimension of the films. KeywordsIon irradiation-electronic excitation-atomic force microscopy
  Indian Journal of Physics and Proceedings of the Indian Association for the Cultivation of Science -New Series- 04/2012; 84(10):1391-1397. · 0.38 Impact Factor
• Article: Structural and magnetic properties of Fe doped NiO

  P. Mallick, Chandana Rath, R. Biswal, N. C. Mishra
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  ABSTRACT: Mott-Hubbard anti-ferromagnetic insulator, NiO shows p-type semiconducting behaviour due to vacancy at Ni2+ site in its bunsenite structure. We report the modification of structural and magnetic order in NiO on Fe doping. NiO samples at different Fe concentrations in the range 0 to 5 at.% have been prepared by chemical co-precipitation and post thermal decomposition method. Both structural and magnetic characterization reveal that with increasing Fe doping concentration, NiO evolves as a magnetically inhomogeneous state out of the parent homogeneous antiferromagnetic state. In addition, structural inhomogeneity was also observed with Fe precipitating to γ-Fe2O3 phase, the signature of which could be clearly seen for Fe content beyond 2 at.%. At lower Fe content however, some amount of Fe occupies lattice and interstitial sites in the NiO matrix and drive the latter to acquire ferromagnetic ordering, which was evident from a clear hysteresis loop at 300 K.
  Indian Journal of Physics and Proceedings of the Indian Association for the Cultivation of Science -New Series- 04/2012; 83(4):517-523. · 0.38 Impact Factor
• Source

  Available from: arxiv.iacs.res.in

  Article: Effect of cobalt substitution on microstructure and magnetic properties in ZnO nanoparticles

  Chandana Rath, Sonal Singh, P. Mallick, D. Pandey, N. P. Lalla, N. C. Mishra
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  ABSTRACT: Ferromagentic semiconductors have been actively pursued because of their potential as spin polarized carrier sources and easy integration into semiconductor technology. One such material, ZnO has been shown to be a potential Diluted Magnetic Semiconductor (DMS). The appearance of ferromagnetism, however, is found to be sensitive to the processing conditions. We report synthesis of ZnO nanoparticles of size ∼20 nm by a simple co-precipitation technique using metal nitrates and NaOH as precipitant. The particles are self-organised and reveal single crystalline behaviour in electron diffraction pattern. Incorporation of Co in ZnO matrix leads not only to the reduction in crystallite size but also to the modification of the structure. At 5% Co, the particles are highly textured. The particles also aggregate and the aggregated mass have nearly rectangular shape as seen through TEM. Increasing Co to 10%, results into further reduction of particle size and the particles self organize in a line, which looks like nanofibers. This alignment of particles increases by increasing the Co content further. This type of growth of nanofibers above Co ≥ 10% is well correlated with the anisotropic peak broadening observed in the XRD spectra. In addition, Co substitute Zn site up to 20% without showing any extra phase in XRD spectra as compared to 7 to 10% in case of bulk. Transport and magnetic studies indicate that conductivity increases with increasing Co content, but carrier mediated ferromagnetism is absent down to 10 K.
  Indian Journal of Physics and Proceedings of the Indian Association for the Cultivation of Science -New Series- 04/2012; 83(4):415-421. · 0.38 Impact Factor
• Conference Proceeding: Evolution of microstructure and surface topography of gold thin films under thermal annealing

  P. Dash, H. Rath, B. N. Dash, P. Mallick, T. Basu, T. Som, U. P. Singh, N. C. Mishra
  International workshop on Functional Materials; 01/2012
• Article: Swift heavy ion irradiation induced modification of BiFeO3 thin films prepared by sol-gel method

  B. N. Dash, Priyadarshini Dash, Haripriya Rath, P. Mallick, R. Biswal, P. K. Kulriya, N. C. Mishra
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  ABSTRACT: We report the preparation of multiferroic BiFeO3 thin films on ITO coated glass substrates through sol-gel spin coating method followed by thermal annealing and their modification by swift heavy ion (SHI) irradiation. X-ray diffraction and Raman spectroscopy studies revealed amorphous nature of the as deposited films. Rhombohedral crystalline phase of BiFeO3 evolved on annealing the films at 550°C. Both XRD and Raman studies indicated that SHI irradiation by 200 MeV Au ions result in fragmentation of particles and progressive amorphization with increasing irradiation fluence. The average crystallite size estimated from the XRD line width decreased from 38 nm in pristine sample annealed at 550°C to 29 nm on irradiating these films by 200 MeV Au ions at 1 × 1011 ions cm−2. Complete amorphization of the rhombohedral BiFeO3 phase occurs at a fluence of 1 × 1012 ions.cm−2. Irradiation by another ion (200 MeV Ag) had the similar effect. For both the ions, the electronic energy loss exceeds the threshold electronic energy loss for creation of amorphized latent tracks in BiFeO3. KeywordsIon irradiation-thin film-multiferroics
  Indian Journal of Physics and Proceedings of the Indian Association for the Cultivation of Science -New Series- 01/2010; 84:1315-1320. · 0.38 Impact Factor
• Article: 200 MeV silver ion irradiation induced structural modification in YBa2Cu3O7-y thin films at 89 K: An in situ x-ray diffraction study

  R. Biswal, J. John, P. Mallick, B. N. Dash, P. K. Kulriya, D. K. Avasthi, D. Kanjilal, D. Behera, T. Mohanty, P. Raychaudhuri, N. C. Mishra
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  ABSTRACT: We report in situ x-ray diffraction (XRD) study of 200 MeV Ag ion irradiation induced structural modification in c -axis oriented YBa ₂ Cu ₃ O _7-y (YBCO) thin films at 89 K. The films remained c -axis oriented up to a fluence of 2×10¹³ ions cm ^-2 , where complete amorphization sets in. The amorphous ion tracks, the strained region around these tracks, and irradiation induced point defects are shown to control the evolution of the structure with ion fluence. Secondary electrons emanating from the ion paths are shown to create point defects in a cylindrical region of 97 nm radius, which corresponds to their maximum range in the YBCO medium. The point defects are created exclusively in the CuO basal planes of fully oxygenated YBCO, which has not been possible, by other techniques including low energy ion irradiation and thermal quenching. The point defects led to a faster decrease in the integral intensity of XRD peaks at very low fluences of irradiation (Φ≤3×10¹⁰ ions cm ^-2) than what can be expected from amorphous tracks. The radius of amorphous ion tracks, estimated from the fluence dependence of integral XRD peak intensity beyond this fluence, was found to be 1.9 nm. Both point defect and the strained region around amorphous ion tracks are shown to contribute to the increase in the c -parameter at 89 K. The full width at half maximum (FWHM) of XRD peaks arising mostly due to the strained region around the ion tracks showed an incubation effect up to 10¹² ions cm ^-2 , before increasing at higher fluences. Fluence dependence of FWHM gives the cro- ss section of the strained region as 37.9 nm ² , which is more than three times the cross section of the amorphous ion tracks.
  Journal of Applied Physics 10/2009; · 2.17 Impact Factor
• Article: Anomalous x-ray diffraction peak broadening and lattice strains in Zn(1-x)Co(x)O dilute magnetic semiconductors.

  Chandana Rath, P Mallick, Dhananjai Pandey, D Sa, A Banerjee, N C Mishra
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  ABSTRACT: Nanocrystalline powders of Zn(1-x)Co(x)O synthesized by the coprecipitation technique show anomalous anisotropic broadening for x>0.05. This peak broadening is shown to be not only due to a reduction in the particle size but also due to a significant strain contribution, as confirmed by Williamson-Hall analysis. The presence of grouped Co(2+) ions, revealing the presence of clusters of high spin Co(2+) with antiferromagnetically coupled spins, as indicated by magnetization studies, seems to be responsible for the strain.
  Journal of Physics Condensed Matter 02/2009; 21(7):075801. · 2.55 Impact Factor
• Article: Surface Roughness and Power Spectral Density Study of SHI Irradiated Ultra-thin Gold Films

  P. Dash, P. Mallick, H. Rath, A. Tripathi, Jai Prakash, D.K. Avasthi, S. Mazumdar, S. Varma, P. V. Satyam, N. C. Mishra
  Applied Surface Science 01/2009; 256:558–561. · 2.10 Impact Factor
• Article: Evolution of surface morphology of NiO thin films under swift heavy ion irradiation

  P Mallick, Chandana Rath, S Majumder, R Biswal, DC Agarwal, Shikha Varma, DK Avasthi, PV Satyam, NC Mishra
  Applied Surface Science 01/2009; 256(2):521-523. · 2.10 Impact Factor
• Source

  Available from: nitrkl.ac.in

  Article: Point defect creation by low fluence swift heavy ion irradiation-induced low energy electrons in YBa2Cu3O7−y

  R Biswal, J John, D Behera, P Mallick, Sandeep Kumar, D Kanjilal, T Mohanty, P Raychaudhuri, N C Mishra
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  ABSTRACT: The effect of 200 MeV Ag ion irradiation on the superconducting and normal state properties of the high-Tc superconductor YBa2Cu3O7−y (YBCO) is studied by in situ temperature-dependent resistance measurements. We show that irradiating YBCO thin films (~150 nm) at low temperature result in a softly defected region of about 85 nm radius due to swift heavy ion-induced secondary electrons around the highly amorphized latent tracks of ~5 nm radius. This leads to a decrease of Tc at fluences three orders of magnitude less than the threshold fluence, where overlapping of tracks block the supercurrent path. Due to their low energy (4.1 keV for 200 MeV Ag ions), the secondary electrons can induce point defects by inelastic processes rather than by direct elastic collision.
  Superconductor Science and Technology 06/2008; 21(8):085016. · 2.66 Impact Factor
• Article: Swift heavy ion irradiation induced modification of the microstructure of NiO thin films

  P. Mallick, Chandana Rath, Jai Prakash, D.K. Mishra, R.J. Choudhary, D.M. Phase, A. Tripathi, D.K. Avasthi, D. Kanjilal, N.C. Mishra
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  ABSTRACT: NiO nanoparticle films (200 nm thick) grown on Si substrates by pulsed laser deposition method were irradiated by 200 MeV Ag15+ ions. The films were characterized by glancing angle X-ray diffraction, atomic force microscopy and optical absorption spectroscopy. Though electronic energy loss of 200 MeV Ag ions in NiO matrix was higher than the threshold electronic energy loss for creation of columnar defects, films remained crystalline with the initial fcc structure even up to a fluence of 5 × 1013 ions cm−2, where ion tracks are expected to overlap. Irradiation however modified the microstructure of the NiO films considerably. The grain size decreased with increasing ion fluence, which led to reduced surface roughness and increased optical band gap due to quantum confinement. These results correlate well with variation of the power spectral density exponent with ion fluence, which indicate that at high ion fluences, the evolution of surface morphology is governed by surface diffusion.
  Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 268(10):1613-1617. · 1.21 Impact Factor
• Article: Antiferro to superparamagnetic transition on Mn doping in NiO

  P. Mallick, Chandana Rath, A. Rath, A. Banerjee, N.C. Mishra
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  ABSTRACT: We report the structural and magnetic properties of Ni1−xMnxO (x=0 to 0.05) prepared by chemical method. Within the XRD resolution, no impurity phases could be detected up to 5 at.% Mn doping in NiO. The fcc structure and the lattice parameter of host NiO matrix is not altered on Mn doping. The average crystallite size was found to remain almost constant (28 nm) up to 3 at.% Mn doping, beyond which it decreases to 21 nm for 5 at.% Mn doping in NiO. The magnetic properties on the other hand showed a drastic change with Mn doping. While 0 and 1 at.% Mn doped NiO showed antiferromagnetic behaviour down to 10 K, 3 and 5 at.% Mn doped NiO were superparamagnetic at 300 K with a blocking temperature of 186 and 171 K respectively. Clear hysteresis loops were thus observed for these samples at 10 K. The distribution of blocking temperature of the Mn doped NiO particles matches well with the distribution of particle size as obtained from TEM. The observed antiferro to superparamagnetic transition on Mn doping in NiO is understood on the basis of Mn occupying Ni site and breaking the translational symmetry of the parent antiferromagnetic correlation.
  Solid State Communications 150:1342-1345. · 1.65 Impact Factor
• Article: Swift heavy ion irradiation induced texturing in NiO thin films

  P. Mallick, D.C. Agarwal, Chandana Rath, R. Biswal, D. Behera, D.K. Avasthi, D. Kanjilal, P.V. Satyam, N.C. Mishra
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  ABSTRACT: NiO thin films grown on Si(1 0 0) substrate by electron beam evaporation and sintered at 500 and 700 °C were irradiated with 120 MeV Au9+ ions. The FCC structure of the sintered films was retained up to the highest fluence (3 × 1013 ions cm−2) of irradiation. In the low fluence (⩽1 × 1013 ions cm−2) regime however, the evolution of the XRD pattern with fluence showed a wide variation, critically depending upon their initial microstructure. Though irradiation is known to induce disorder in the structure, we observe improvement in crystallization and texturing at intermediate fluences of irradiation.
  Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms.