Publications (9)8.15 Total impact
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Article: Investigation of structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nano powders prepared by self combustion method
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ABSTRACT: Nano powders of Ni0.5Zn0.5Fe2O4 have been synthesized by the self-combustion method at a relatively low temperature of 473 K under conditions of non-uniform and uniform heating. Rietveld fitting of X-ray diffractograms confirm the formation of the pure spinel phase in both samples. Transmission electron microscopy indicates that the sample prepared under non-uniform heating has a bimodal particle size distribution (average values 16 nm and 6 nm) while the one prepared under uniform heating has a very narrow particle size distribution (average size 4 nm). Low temperature, in-field Mo¨ ssbauer spectroscopic studies clearly show surface spin contributions. The hyperfine fields and Curie temperature of the non-uniformly heated sample are in good agreement with those reported for the corresponding bulk samples. Despite having a very narrow particle size distribution, the uniformly heated sample has a large anisotropy distribution which is evident in the broad transition visible in the temperature dependent magnetization curve. It is also corroborated by the fact that the experimental magnetization curve at room temperature requires two Langevin functions for satisfactory reproduction.Materials Research Bulletin 02/2013; 48(2):698-704. · 2.11 Impact Factor -
Article: Magnetic and transport properties in thin film of Fe2CrAl
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ABSTRACT: Preliminary results on magnetic and transport properties of a thin film of disordered Fe2CrAl deposited on (111) Si by pulsed laser deposition is reported in this study. While the bulk, arc melted ingot used as target for the deposition is purely ferromagnetic, the film shows the co-existence of different magnetic phases which arises due to the granular nature of the film. This is because although the average composition pertains to Fe2CrAl, local disorder results in the formation of grains with different magnetic states which can be ferromagnetic or consisting of magnetic clusters. The resulting magnetic inhomogenity of the thin film leads to large values of negative temperature coefficient of resistance of ~22%/K at 260 K.Journal of Experimental Nanoscience 05/2012; · 1.01 Impact Factor -
Article: Magnetic and transport properties in thin film of Fe2CrAl
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ABSTRACT: Preliminary results on magnetic and transport properties of a thin film of disordered Fe2CrAl deposited on (111) Si by pulsed laser deposition is reported in this study. While the bulk, arc melted ingot used as target for the deposition is purely ferromagnetic, the film shows the co-existence of different magnetic phases which arises due to the granular nature of the film. This is because although the average composition pertains to Fe2CrAl, local disorder results in the formation of grains with different magnetic states which can be ferromagnetic or consisting of magnetic clusters. The resulting magnetic inhomogenity of the thin film leads to large values of negative temperature coefficient of resistance of ~22%/K at 260 K.Journal of Experimental Nanoscience 05/2012; · 1.01 Impact Factor -
Article: Low temperature Mössbauer and DC magnetization studies in nano-sized Ni substituted Co–Zn ferrites
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ABSTRACT: Studies in the series of nano ferrites pertaining to the stoichiometry NixCo0.5 − xZn0.5Fe2O4, (0≤ x ≤0.5) show that contrary to the trend in bulk Co–Zn and Ni–Zn ferrites, the observed saturation magnetization of Ni–Zn ferrite (x = 0.5) is larger than Co–Zn ferrite (x = 0) and are due to finite size effects. This is evident from calculations which show that the magnetic particle sizes are 1.6 nm for Co–Zn ferrite and 2.4 nm for Ni–Zn whereas their average crystallite sizes are 5 to 3 nm respectively. Low temperature Mössbauer spectroscopic studies show that this can be attributed to an increase in an ordered core with the increase in Ni content which is reflected as a corresponding increase in the saturation magnetization.Hyperfine Interactions 01/2011; 199(1-3):403-412. · 0.21 Impact Factor -
Conference Proceeding: MOKE Study of Fe∕Co∕Al Multilayers
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ABSTRACT: The multilayer system (MLS)‐[Fe57/Co/Al]×20 has been deposited by Ion beam sputtering (IBS) technique. The MLS has been annealed at 700 °C for 1 h. Overall composition of as deposited and annealed MLS have been characterized by EDX and magnetic properties have been studied through angular dependent magneto optic Kerr effect (MOKE) hysteresis curves. The study shows that the as‐deposited MLS has excellent soft magnetic properties coupled with perpendicular magnetic isotropy which is destroyed on annealing.SOLID STATE PHYSICS, PROCEEDINGS OF THE 55TH DAE SOLID STATE PHYSICS SYMPOSIUM 2010, Manipal, (India); 12/2010 -
Chapter: Investigation of magnetic properties in 57Fe/Al multilayers
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ABSTRACT: Fe/Al multilayer thin films prepared by ion beam sputtering, with an overall atomic concentration ratio of Fe/Al = 1:2 have been studied by x-ray diffraction spectroscopy (XRD), X-ray reflectivity (XRR) and D.C. Magnetization. These studies show the formation of Fe–Al intermetallic layers. Two magnetic regions and transition temperatures of 473 and 533K are evident from magnetization studies. Conversion Electron Mössbauer Spectroscopy (CEMS) shows formation of off-stoichiometric Fe3Al like phase and phases consisting of pure Fe and Fe-rich extended Fe–Al solutions.04/2009: pages 703-708; -
Article: Phase evolution in 57Fe/Al multilayers studied through dc magnetization, conversion electron Mössbauer spectroscopy, and transmission electron microscopy
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ABSTRACT: Fe/Al multilayer thin films with an overall atomic concentration ratio of Fe : Al =1:2 have been prepared by ion-beam sputtering. Phase formation and microstructural evolution with thermal annealing have been studied by x-ray reflectivity, cross-sectional transmission electron microscopy, dc magnetization, and conversion electron Mössbauer spectroscopy. These studies show that although the starting composition is Al rich, the intermixing of Fe and Al at the interfaces leads to the formation of a magnetic Fe <sub>3</sub> Al -like region at the interface. Thus, the magnetic contribution in the as-deposited multilayer structure (MLS) is not only from pure Fe but also from an Fe <sub>3</sub> Al -like region formed at the interface. On annealing the MLS, a stable nonmagnetic MLS consisting of intermetallic B2 Fe <sub>50</sub> Al <sub>50</sub> separated by thin Al layers is formed. Further annealing only induces better ordering of Fe <sub>50</sub> Al <sub>50</sub> and does not destroy the MLS.Journal of Applied Physics 01/2009; · 2.17 Impact Factor -
Article: Evolution of structural and magnetic properties of FePt/C granular films with thermal annealing
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ABSTRACT: We report the structural and magnetic properties of as-deposited and thermally annealed FePt/C granular multilayer films. The as-deposited system exhibits a disordered fcc FePt phase with an average grain size of 3 nm. Thermal annealing at 650 °C results in partial L10 ordering and an associated grain growth to 7 nm. Mössbauer measurements show that there is no non-magnetic component present, suggesting that carbon resides only in the grain boundary region. The ferromagnetic grains are magnetically decoupled.Highlights► FePt/C granular films prepared by Ion beam sputtering. ► FePt nanoparticles. ► Evolution of superlattice peaks by thermal annealing. ► Formation of magnetically decoupled phases.Solid State Communications 151(10):794-797. · 1.65 Impact Factor -
Article: Magnetic properties resulting from core-shell interactions in nanosized Ni_ {0.25} Co_ {0.25} Zn_ {0.5} Fe_ {2} O_ {4}
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ABSTRACT: Nanosized particles of Ni0.25Co0.25Zn0.5Fe2O4 have been synthesized by chemical coprecipitation method. Exchange-bias phenomenon arising from the core-shell interaction has been investigated using a combination of in-field, low-temperature Mössbauer spectroscopy and dc magnetization. To understand the clear mechanism of interaction and exchange bias, isothermal remanence magnetization-dc demagnetization and M-H loops at different cooling field have been taken. The observed variation in coercivity HC and exchange-bias field HE confirms that only core is affected by the cooling field. The slope of the Henkel plot is 1.82, indicating the noninteracting nature of the particles. In-field Mössbauer spectroscopy clearly establishes the core and shell contributions and also confirms that 70% of spins are in the shell. The barrier energy has been estimated to be 17×10−14 ergs which accounts for the fact that the shell is not affected by application of as large a field as 5 T.Phys. Rev. B. 80(17).
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2009
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UGC-DAE Consortium for Scientific Research
Indore, State of Madhya Pradesh, India
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