Selected Publications

1. Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT. D.M. Evans, A. Schilling, Ashok Kumar, D. Sanchez, N. Ortega, M. Arredondo, R.S. Katiyar, J.M. Gregg and J.F. Scott. Nature Communications |4:1534 | DOI: 10.1038/ncomms2548, (2013) the above article is highlighted by Nature India.

2. Magnetoelectric memory at room temperature, Nature India, Research highlight, Ashok kumar Doi:10.1038/nindia.2013.43; Published online 26 March 2013

3. Magnetic Switching of Ferroelectric Domains at Room Temperature in a New Multiferroic, J. F. Scott, D. M. Evans, J. M. Gregg, Ashok Kumar, D. Sanchez, N. Ortega, R. S. Katiyar, Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany, DOI: 10.1002/9783527667703.ch22, (2013).

4. Advanced high-k gate dielectric amorphous LaGdO3 gated MOS devices with sub-nanometer EOT, S. P. Pavunny, Pankaj Misra, Reji Thomas, Ashok Kumar, Jürgen Schubert, J. F. Scott , Ram S. Katiyar, Appl. Phys. Lett., 102, 192904, (2013)

5.Room-Temperature Single Phase Multiferroic Magnetoelectrics: Pb(Fe, M)_x(Zr,Ti)_(1-x)O₃ [M = Ta, Nb]. Dilsom A. Sanchez, Nora Ortega, Ashok Kumar, G. Sreenivasulu, Ram S. Katiyar, J. F. Scott, Donald M. Evans, Miryam Arredondo-Arechavala, A. Schilling, and J. M. Gregg. J. Appl. Phys. 113, 074105 (2013).

6. Switching Ferroelectric Domain Configurations using both Electric and Magnetic Fields in Pb(Zr,Ti)O₃-Pb(Fe,Ta)O₃ Single Crystal Lamellae. D. M. Evans, A. Schilling, Ashok Kumar, D. Sanchez, N. Ortega, R. S. Katiyar, J. F. Scott4 and J. M. Gregg. Phil. Trans. R. Soc. A. (In Press, 2013) (Royal Society of Chemistry).

7. Photoluminescence and Time-Resolved Spectroscopy in Multiferroic BiFeO3: Effects of Electric Fields and Sample Aging, A Anshul, A Kumar, B K Gupta, R K Kotnala, J F Scott, R S Katiyar, Appl. Phys. Lett. 102, 222901 (2013).

8. Magnon Raman spectroscopy and in-plane dielectric response in BiFeO₃:Relation to the Polomska transition, Ashok Kumar, R. S. Katiyar, J F Scott, Phys. Rev. B, 85, 224410 (2012).

9. New Recipe of memory devices, Nature India, Research highlight, Ashok kumar DOI: 10.1038/nindia.2012.64; (2012).

10. In-plane Dielectric and Magnetoelectric Studies of BiFeO₃, Ashok Kumar, R. S. Katiyar, R martinez, J F Scott, G Srinivasan, Phys. Status Solidi A, 1–6 (2012); DOI 10.1002/pssa.201228154. One of Figures corresponding to the above article was chosen as cover of the Phys. Status Solidi A (pss)

11. Ferroelectric-Carbon Nanotube Memory Devices, Ashok Kumar, Sai G. Shivareddy, Margarita Correa, Oscar Resto, Youngjin Choi, Ram. S. Katiyar, James. F. Scott, Gehan A. J. Amaratunga, Haidong Lu, Alexe. Gruverman, Nanotechnology, 23 165702, (2012).

12. Phase Transition and Temperature Stability of Piezoelectric Properties in Mn-modified Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 Ceramics, Yongke Yan , Ashok Kumar , Margarita Correa , Kyung-Hoon Cho , R. K. Katiyar, S. Priya, Appl. Phys .lett, 100, 152902 (2012) .

13. Nanostructured Lead–Free Ferroelectric Na0.5Bi0.5TiO3-BaTiO3 Whiskers: Synthesis Mechanism and Structure, Deepam Maurya, Valeri Petkov, Ashok Kumar, Shashank Priya, Dalton Transactions (Royal Society of Chemistry), 41, 5643, (2012).

14. Optical properties of amorphous high-k LaGdO3 films and its band alignment with Si, S.P. Pavunny, R. Thomas, A. Kumar, E. Fachini and R.S. Katiyar, Journal of Applied Physics, 111, 044106 (2012).

15. X-ray diffraction investigation of BaTiO₃/(Ba,Sr)TiO₃ Superlattice, OA Maslova, I. N. Zakharchenkoa, O. A. Bunina, Y. I. Yuzyuk, N. Ortega, A. Kumar, R. S. Katiyar, Physics of the Solid State, 54, 1014 ( 2012).

16. Spontaneously detaching self-standing diamond films, Deepak Varshney, Ashok Kumar, Maxime J-F Guinel, Brad R. Weiner, Gerardo Morell, Diamond and related materials, Diamond & Related Materials 21, 99–102, (2012)

17. Conformal Coating of Functional Ferroelectric Oxides on Carbon Nanotubes, Frank Mendoza, Ashok Kumar, Ricardo Martinez, J. F. Scott, Brad Weiner, R. S Katiyar and Gerardo Morell, Europiean Physics Letters, 97, 27001, (2012)

18. Symmetries and Multiferroic Properties of (PbZr0.53Ti0.47O3) (1-x)-(PbFe0.5Ta0.5O3)x Ceramics, Dilsom Sanchez, Ashok Kumar, Nora Ortega, R. S. Katiyar, J. F. Scott, AIP Advances, 1, 042169 (2011).

19. Photovoltaic effect in a wide-area semiconductor-ferroelectric device, R. K. Katiyar, A. Kumar, G. Morell1, J. F. Scott, R. S. Katiyar, Appl. Phys. Lett. 99, 092906 (2011).

20. Barium zirconate titanate-Barium calcium titanate ceramic materials prepared by sol-gel process: Novel high energy density capacitors, Venkata S Puli, Ashok Kumar, Douglas B. Chrisey, M.Tomazawa, J.F. Scott, and, Ram S.Katiyar, J. Phys. D: Appl. Phys. 44, 395403, (2011).

21. Electric control of Magnon, phonon and magnetic moment in BiFeO₃ : Direct evidence of magneto-electric coupling, Ashok Kumar, J.F. Scott, and, Ram S.Katiyar, Applied Physics letters, 99, 062504 (2011)

22. Birelaxors, Ashok Kumar, J.F. Scott, and, Ram S.Katiyar, Applied Physics letters, 99, 042907 ( 2011).

23. Phonon anomalies and phonon-spin coupling in multiferroic PbFe0.5Nb0.5O3 thin film, M. Correa, Ashok Kumar, S.Priya, J. F. Scott and R. S. Katiyar, Physical Review B, 83, 014302 (2011).

24. Magnetic Control of Ferroelectric Interfaces, S. Dussan, A. Kumar, R. S. Katiyar, S. Priya, and J. F. Scott, Journal of Physics: condesed matter, 23, 202203, (2011).

25. Impedance spectroscopy analysis of Ba0.7Sr03TiO3/La0.7Sr0.3MnO3 heterostructure, R Martínez, A Kumar, R Palai, J F Scott and R S Katiyar, J. Phys. D: Appl. Phys., 44, 105302, (2011).

26. Fabrication and electron emission of diamond films from kitchen-wrap polyethylene, Deepak Varshney, Vladimir I. Makarov, Puja Saxena, Maxime J-F Guinel, Ashok Kumar, James F. Scott, Brad R. Weiner, and Gerardo Morell, J. Phys. D: Appl. Phys.,44, 085502, (2011)

27. Effect of the Periodicity and the Composition in artificial BaTiO3/ (Ba,Sr)TiO3 superlattices, N. Ortega, A. Kumar, O.A. Maslova, Yu. I. Yuzyuk, J. F. Scott and R. S. Katiyar, Physical Review B, 83, 144108, (2011).

28. Room-temperature multiferroic effects in superlattice nano-capacitors, S. Dussan, Ashok Kumar, S.Priya, J. F. Scott and R. S. Katiyar, Applied Physics Letters, 97, 252902 (2010).

29. Near Room Temperature Relaxor Multiferroic, Dilson Sanchez, Ashok Kumar, N.Ortega,J.F. Scott and R. S. Katiyar, Applied Physics Letters, 97, 202910 (2010)).

30. Novel room temperature magnetoelectric Multiferroics for Random Access Memory Elements, Ashok Kumar, J. F. Scott and R. S. Katiyar, IEEE Transactions Ultrasonics, Ferroelectrics, and Frequency Control, 57, 2237, (2010).

31. Raman Spectroscopy and Field Emission characterization of Delafossite CuFeO₂ at ambient temperature, Shojan P., Ashok Kumar, R.S. Katiyar, J. App. Phys., 107, 013522 (2010).

32. Magnetic Effects on Dielectric and Polarization Behavior of Multiferroic Hetrostructures Sandra Dussan, Ashok Kumar, J. F. Scott, and Ram S. Katiyar, Applied Physics Letters 96, 072904,( 2010).

33. Structural, electrical, and magnetic characterization of Ferroelectric/Ferromagnetic hetrostructures, R. Martínez Ashok Kumar, R. Palai, R. S. Katiyar, and J. F. Scott, J. App. Phys., 107, 114107,(2010).

34. Fabrication and Characterization of the Multiferroic bi-Relaxor Lead-iron-tungstate/lead-zirconate-titanate, Ashok Kumar, J. F. Scott and R. S. Katiyar, Journal of Applied Physics, 108, 064105, (2010).

35. Investigation of temperature dependent polarization, dielectric, and magnetization behavior of multiferroic layered nanostructure, N. Ortega, Ashok Kumar, C. Rinaldi and Ram S. Katiyar, Thin Solid Films, 519, 641, (2010).

36. Fabrication and Characterization of Relaxor Ferroelectric PbFe_1/2Ta_1/2O₃ Thin Film: A Comparison with Ceramics, R. Martínez V, Ashok Kumar, Dilsom A Sanchez, R. Palai, and R. S. Katiyar Journal of Applied Physics,108, 084105, (2010).

37. Magnetic control of large room-temperature polarization, Ashok Kumar, G. L. Sharma, R.S. Katiyar, J. F. Scott, R. Pirc, R. Blinc, J. Phys. Condens. Matter 21, 382204 (2009)(Top 25 papers of 2009, JPCM).

38. Relaxed Coupling, Ashok Kumar et al. “Nature Materials” Research highlight, 8, 772, (2009).

39. Structural and optical properties of N doped ZnO nanorod arrays, Boqian Yang, Ashok Kumar, Peter Feng, Marc Achermann and R. S. Katiyar, J. Phys. D: Appl. Phys. 42, 195402 (2009).

40. Positive temperature coefficient of resistivity and negative differential resistivity in lead iron tunstate-lead zirconate titanate Ashok Kumar, R.S. Katiyar, J. F. Scott, Applied Physics Letters94, 212903, (2009).

41. Investigation of Local Structure of Lead Free Relaxor Ba(Ti_0.70Sn_0.30)O₃ by Raman Spectroscopy, Ashok Kumar, Iris Rivera and R.S. Katiyar, Journal of Raman Spectroscopy 40, 459, (2009).

42. Growth of ZnO nanostructures on different substrates using the pulsed laser deposition technique, Boqian Yang, Ashok Kumar, Noel Upia, Peter Feng, and R. S. Katiyar, Journal of Phys D:Applied Physics, 42, 045415, (2009).

43. Synthesis and characterization of nanocrystalline dysprosia stabilized zirconia based electrolyte for intermediate-temperature solid oxide fuel cell, S. Maiti, M. Pastor, R.S. Sundaram, J. Ravichandran, A. Kumar, K. Biswas and I. Manna, Journal of Alloys and Compounds, 475, 587, (2009).

44. Divide line between relaxor, diffused ferroelectric, ferroelectric and dielectric, Iris Rivera, Ashok Kumar, and R.S. Katiyar, Solid State communications 149, 433, (2009).

45. Magneto-Electric coupling in glassy epitaxial PbFe_0.5Nb_0.5O₃ thin films, Margarita Correa, Ashok Kumar, R. S. Katiyar, and Carlos Rinaldi, Applied physics Letters 93, 192907, (2008).

46. Size and Strain effects on relaxor ferroelectric properties of PbSc_0.5Nb_(1-x)/2Ta_x/2O₃ thin films and nanoceramics Margarita Correa, Ashok Kumar, R. S. Katiyar, Integrated Ferroelectrics 100, 297, (2008) Editors choice.

47. Glass-like state in PbFe_1/2Nb_1/2O₃ single crystal Ashok Kumar, R. S. Katiyar Carlos Rinaldi Sergey G Lushnikov, Tatjana A. Shaplygina, Applied physics Letters 93, 232902, (2008).

48. Impedance spectroscopic studies of the multiferroics Pb(Zr,Ti)O₃-CoFe₂O₄ layered thin films, N. Ortega, Ashok Kumar, P. Bhattacharya, S.B. Majumder and R.S. Katiyar, Physical Review B 77, 014111 (2008).

49. Multiferroic Pb(Fe_0.66W_0.33)_0.80Ti_0.20O₃ thin films: A room-temperature relaxor ferroelectric and weak ferromagnetic Ashok. Kumar, I. Rivera, and R.S. Katiyar, Applied Physics Letters, 92, 132913, (2008).

50. Reduced leakage current in chemical solution deposited multiferroic BiFeO₃/Ba_0.25Sr_0.75TiO₃ hetero-structured thin films on platinized silicon substrates, N.M. Murari, Ashok Kumar, R. Thomas, and R.S. Katiyar, Applied. Physics, Letters, 92, 132904 (2008).

51. Study of optical phonons lifetimes near the diffuse phase transition in relaxor ferroelectric, Margarita Correa, Ashok Kumar, J. F. Scott and R. S. Katiyar, Journal of Physics: Condensed Matter 20, 125211, (2008).

52. Observation of one magnon and magnon-phonon-electric dipole coupling in multiferroics bismuth ferrite thin films Ashok. Kumar, N.M. Murari, and R.S. Katiyar Applied. Physics, Letters, 92, 152907, (2008).

53. Ionic conductivity and electrical relaxation of nanocrystalline Scandia Stabilized c- zirconia using Complex impedance analysis Ashok Kumar, I. Manna Physica B: condensed matter, 408, 2298, (2008).

54. New phase transitions in peroveskites; BiFeO₃, SrSnO₃ and Pb(Fe_2/3W_1/3)_0.50Ti_0.50O₃ J. F. Scott, R. Palai, A. Kumar, M. K. Singh, N. K. Karan, N. M. Murari and R.S. Katiyar, J. Am. Cer. Soc., 91(6), 1762, (2008).

55. Strain induced relaxor behavior in PbSc_0.5Nb_0.25Ta_0.25O₃ thin films: A comparison with nanoceramics. Margarita Correa, Ashok. Kumar and R.S. Katiyar, J. Am. Cer. Soc., 91 (6), 1788, (2008).

56. Enhanced polarization and dielectric properties of Pb(Zr_1-xTi_x)O₃ thin films, N. Ortega, Ashok Kumar, and R.S. Katiyar, Journal of Applied Physics, 104, 074114 (2008).

57. Structural degradation and optical property of nanocrystalline ZnO thin films grown on Si (100), Boqian Yang, Ashok Kumar, Peter Feng, and R.S. Katiyar, Applied physics Letters 91, 233112 (2008).

58. Diffused Phase Transition and Relaxor behavior in Pb(Fe_2/3W_1/3)O₃ thin films, Ashok Kumar, N. M. Murari, R. S. Katiyar, Applied Physics Letters 90, 162903 (2007).

59. Probing the ferroelectric phase transition through Raman spectroscopy in Pb(Fe_2/3W_1/3)_1/2Ti_1/2O₃ thin films, Ashok Kumar, N. M. Murari, R. S. Katiyar, Applied Physics Letters 90 262907, (2007).

60. Investigation of frequency dependent and independent dielectric maxima in relaxor ferroelectric thin films, Margarita Correa, Ashok Kumar, and R. S. Katiyar, Applied Physics Letters 91 082905 (2007).

61. Maxwell-Wagner space charge effects on the Pb(Zr,Ti)O₃-CoFe₂O₄ multilayers, N. Ortega, Ashok Kumar, and R.S. Katiyar, Applied Physics Letters 91 102902 (2007).

62. Characterization of Electrical Properties of Pb modified BaSnO₃ using impedance spectroscopy, Ashok Kumar, R. N. P. Choudhary, B. P. Singh and Awlendra K. Thakur, Materials Chemistry and Physics, 99, 150 (2006).