@article{GuptaGuptaLeitenbergeretal.2012,
  author    = {Gupta, Ranjeeta and Gupta, Ajay and Leitenberger, Wolfram and R{\"u}ffer, R.},
  title     = {Mechanism of stress relaxation in nanocrystalline Fe-N thin films},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {85},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {7},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1098-0121},
  doi       = {10.1103/PhysRevB.85.075401},
  pages     = {7},
  year      = {2012},
  abstract  = {The mechanism of stress relaxation in nanocrystalline Fe-N thin film has been studied. The as-deposited film possesses a strong in-plane compressive stress which relaxes with thermal annealing. Precise diffusion measurements using nuclear resonance reflectivity show that stress relaxation does not involve any long-range diffusion of Fe atoms. Rather, a redistribution of nitrogen atoms at various interstitial sites, as evidenced by conversion electron Mossbauer spectroscopy, is responsible for the relaxation of internal stresses. On the other hand, formation of the. gamma'-Fe4N phase at temperatures above 523 K involves long-range rearrangement of Fe atoms. The activation energy for Fe self-diffusion is found to be 0.38 +/- 0.04 eV.},
  language  = {en}
}
@article{ReddyGuptaGomeetal.2009,
  author    = {Reddy, Raghavendra V. and Gupta, Ajay and Gome, Anil and Leitenberger, Wolfram and Pietsch, Ullrich},
  title     = {In situ x-ray reflectivity and grazing incidence x-ray diffraction study of L1(0) ordering in Fe-57/Pt multilayers},
  issn      = {0953-8984},
  doi       = {10.1088/0953-8984/21/18/186002},
  year      = {2009},
  abstract  = {In situ high temperature x-ray reflectivity and grazing incidence x-ray diffraction measurements in the energy dispersive mode are used to study the ordered face-centered tetragonal (fct) L1(0) phase formation in [Fe(19 angstrom)/ Pt(25 angstrom)](x10) multilayers prepared by ion beam sputtering. With the in situ x-ray measurements it is observed that (i) the multilayer structure first transforms to a disordered FePt and subsequently to an ordered fct L1(0) phase, (ii) the ordered fct L1(0) FePt peaks start to appear at 320°C annealing, (iii) the activation energy of the interdiffusion is 0.8 eV and (iv) ordered fct FePt grains have preferential out-of-plane texture. The magneto-optical Kerr effect and conversion electron Mossbauer spectroscopies are used to study the magnetic properties of the as- deposited and 400°C annealed multilayers. The magnetic data for the 400°C annealed sample indicate that the magnetization is at an angle of ~50° from the plane of the film.},
  language  = {en}
}
@article{BrajpuriyaTripathiSharmaetal.2007,
  author    = {Brajpuriya, Ranjeet and Tripathi, Sumit and Sharma, Abhishek and Chaudhari, S.M. and Phase, D.M. and Gupta, Ajay and Shripathi, Thoudinja and Leitenberger, Wolfram and Pietsch, Ullrich and Laxmi, N.},
  title     = {Temperature dependent energy-dispersive X-ray diffraction and magnetic study of Fe/Al interface},
  issn      = {0169-4332},
  doi       = {10.1016/j.apsusc.2007.04.069},
  year      = {2007},
  abstract  = {In situ temperature dependent energy-dispersive structural and magnetic study of electron beam evaporated Fe/Al multilayer sample (MLS) has been investigated. The structural studies show the formation of an intermixed FeAl transition layer of a few nanometers thick at the interface during deposition, which on annealing at 300 degrees C transforms to B2FeAl intermetallic phase. Magnetization decreases with increase in temperature and drops to minimum above 300 degrees C due to increase in anti-ferromagnetic interlayer coupling and formation of nonmagnetic FeAl phase at the interface. The Curie temperature (T-c) is found to be 288 degrees C and is much less than that of bulk bcc Fe.},
  language  = {en}
}
@article{PietschGuptaGuptaetal.2004,
  author    = {Pietsch, Ullrich and Gupta, Ajay and Gupta, Mukul and Ayachit, S. and Rajagopalan, S. and Balamurgan, A. K. and Tyagi, A. K.},
  title     = {Iron self-diffusion in nanocrystalline FeCr thin films},
  year      = {2004},
  abstract  = {Thin films of amorphous Fe85Zr15 alloy were deposited by ion-beam sputtering of a composite target. Analogous to the melt-spun amorphous alloys of similar composition, the crystallization of the amorphous film occurs in two steps, however, with a substantially reduced thermal stability. After completion of the first crystallization step which starts at 473 K, the microstructure consists of 12 nm nanocrystals of bcc-Fe embedded in a grain boundary region of the remaining amorphous phase. At 673 K, the remaining amorphous phase transforms into the Fe2Zr alloy. The self-diffusion measurements of iron in the nanocrystalline state and in the parent amorphous state has been carried out using secondary ion mass spectroscopy (SIMS) depth profiling and neutron reflectivity techniques. In contrast to the case of finemet Fe73.5Si13.5B9Nb3Cu1 alloy, where a significant enhancement of diffusivity takes place in the nanocrystalline state, in the present case the diffusivity in the nanocrystalline state is similar to that in the parent amorphous state. It is suggested that in this system the atomic diffusion occurs mainly via the grain boundary regions. The calculated values of the pre-exponential factor and the activation energy for the diffusion are D-0 = 1 x 10(-14+/-1) m(2)/s and E = (0.7 +/- 0.1) eV respectively. (C) 2004 Published by Elsevier B.V.},
  language  = {en}
}
@article{ReddyPuranikGuptaetal.2007,
  author    = {Reddy, Raghavendra V. and Puranik, Shikha and Gupta, Ajay and Leitenberger, Wolfram},
  title     = {Study of FePt films prepared by reactive sputtering},
  year      = {2007},
  language  = {en}
}