Skip to main content

Dr. Kevin Coffey

Professor

MSE

Education

  • Ph.D. — Massachusetts Institute of Technology, 1989

Research

  • Thin Film Processing
  • Magnetic Materials
  • Solid State Reactions
  • Nanoscale Tribology
  • Magnetic Thin Films
  • Grain Boundary Diffusion
Dr. Coffey’s research interests include both magnetism and the materials science of nano-scale interfaces. Materials systems such as the high magneto-crystalline anisotropy FePt ordered intermetallic phases are of special interest because of a strong relationship between magnetic properties and nanoscale microstructure. Additionally, this system promises to be an ideal model system for the study of bulk permanent magnet materials because of the large range of microstructure variation that can be readily obtained. Dr. Coffey’s work includes a study of magnetic switching in various nanoscale permanent magnet thin films used for magnetic recording as well as the processing, structure, and properties of FePt and other L10 phase magnetic thin films, as well as giant magnetoresistance is soft magnetic thin film structures. The oxidative and thermal stability of nanoscale microstructures is important to the potential use of such devices and effected greatly by relatively large amount of interfacial area present in such devices. Dr. Coffey’s work and interests include the oxidation and interdiffusion of thin film structures where the kinetics are strongly dependent on interfacial transport.

Selected Publications

  1. "Conical dark field scanning for grain size measurement in thin films", A. Darbal, K. Barmak, D. Choi, X. Liu, T. Sun, B. Yao, A. Warren, K. R. Coffey, Micron, submitted for publication.
  2. "Grain growth and the puzzle of its stagnation in thin Films: A detailed comparison of experiments and simulations", K. Barmak, E. Eggeling, R. Sharp, S. Roberts, T. Shyu, T. Sun, B. Yao, S. Ta’san, D. Kinderlehrer, A. Rollett, K. R. Coffey, Materials Science Forum, in press.
  3. "Determination of optimum Si excess concentration in Er-doped Si-rich SiO2 for optical amplification at 1.54 mu m," O. Savchyn, K. R. Coffey, P. G. Kik, Applied Physics Letters, vol. 97, Article 201107, 2010
  4. "High-temperature optical properties of sensitized Er3+ in Si-rich SiO2 - implications for gain performance," O. Savchyn, R. M. Todi, K. R. Coffey, P. G. Kik, Optical Materials, vol. 32, Pages 1274-1278, 2010
  5. "Surface and grain boundary scattering in nanometric Cu films," T. Sun, B. Yao, A.P. Warren, K. Barmak, M.F. Toney, R.E. Peale, and K. R. Coffey, Physical Review B, Vol. 81, Article 155454, 2010.
  6. "High contrast hollow-cone dark field transmission electron microscopy for nanocrystalline grain size quantification," B. Yao, T. Sun, A. Warren, H. Heinrich, K. Barmak, and K. R. Coffey, Micron, Volume 41, Pages 177-182, 2010.
  7. "Effect of thin silicon dioxide layers on resonant frequency and amplitude in infrared metamaterials," D.J. Shelton, D.W. Peters, M.B. Sinclair, I. Brener, L.K. Warne, L.I. Basilio, K.R. Coffey, G. D. Boreman, Optics Express, Col. 18, Pages 1085-1090, 2010.
  8. "Experimental demonstration of tunable phase in a thermochromic infrared-reflectarray metamaterial," D.J. Shelton, K.R. Coffey, G. D. Boreman, Optics Express, Vol. 18, Pages 1330-1335, 2010.
  9. "Excitation wavelength independent sensitized Er3+ concentration in as-deposited and low temperature annealed Si-rich SiO2 films," O. Savchyn, R. M. Todi, K. R. Coffey, L. K. Ono, B. R. Cuenya, P. G. Kik, Applied Physics Letters, vol. 95, Article 231109, 2009.
  10. "Thickness dependence of structure and magnetic properties of annealed [Fe/Pt]n multilayer films, " B. Yao and K.R. Coffey, Journal of Applied Physics, vol. 105, Article 07A726, 2009.
  11. "Observation of temperature-independent internal Er3+ relaxation efficiency in Si-rich SiO2 films," O. Savchyn, R. M. Todi, K. R. Coffey, and P. G. Kik, Applied Physics Letters, vol. 94, Article 241115, 2009.
  12. "Quantification of L10 phase volume fraction in annealed [Fe/Pt]n multilayer films," B. Yao and K.R. Coffey, Journal of Applied Physics, vol. 105, Article 033901, 2009.
  13. "Dominant role of grain boundary scattering in the resistivity of nanometric Cu films" T. Sun, B. Yao, A.P. Warren, K. Barmak, M.F. Toney, R.E. Peale, and K. R. Coffey, Physical Review B, vol. 79, Article 041402, 2009.
  14. "Relaxation time effects on dynamic conductivity of alloyed metallic thin films in the infrared band," D. Shelton, T. Sun, J. Ginn, K. Coffey, and G. Boreman, Journal of Applied Physics, vol. 104, Article. 103514, 2008.
  15. "Multilevel sensitization of Er3+ in low-temperature-annealed silicon-rich SiO2," O. Savchyn, R. M. Todi, K. R. Coffey, and P. G. Kik. Applied Physics Letters, vol. 93, Article 233120, 2008.
  16. "A high-throughput approach for cross-sectional transmission electron microscopy sample preparation of thin films," B. Yao and K. R. Coffey, Journal of Electron Microscopy, Vol. 57, no., 6, p. 189-194, 2008.
  17. "On the phase identification of dc magnetron sputtered Pt-Ru alloy thin films," A.P. Warren, R. M. Todi, K. Barmak, K.B. Sundaram, and K. R. Coffey, Journal of Vacuum Science and Technology, A, vol. 26, no. 26, p. 1208-1212, 2008.
  18. "Classical size effect in oxide-encapsulated Cu thin films: impact of grain boundaries versus surfaces on resistivity," T. Sun, B. Yao, A. P. Warren, S. Roberts, V. Kumar, K. Barmak, K. R. Coffey, Journal of Vacuum Science and Technology, A, vol. 26, no. 4, p. 605-609, 2008.
  19. "Grain growth and void formation in dielectric-encapsulated Cu thin films," B. Yao, T. Sun, V. Kumar, K. Barmak, K. R. Coffey, Journal of Materials Research, vol. 23, no. 7, p. 2033-2039, 2008.
  20. "Effect of hydrogen passivation on lumimescence-center-mediated Er excitation in Si rich SiO2 with and without Si nanocrystals," O. Savchyn, P. G. Kik, R. M. Todi, K. R. Coffey, H. Nukala, and H. Heinrich, Physical Review B, vol. 77, no. 20, Article 205438, 2008.
  21. "The effective interdiffusivity, structure, and magnetic properties of [Fe/Pt](n) multilayer films", B. Yao, and K.R. Coffey, Journal of Applied Physics, Vol. 103, no. 7, Article 07E107, 2008.
  22. "Luminescence-center-mediated excitation as the dominant Er sensitization mechanism in Er-doped silicon-rich SiO2 films," O. Savchyn, F. R. Ruhge, P. G. Kik, R. M. Todi, K. R. Coffey, H. Nukala, and H. Heinrich. Physical Review B, vol. 76, article 195419. 2007.
  23. "Back-etch method for plan view transmission electron microscopy sample preparation of optically opaque films,´ B. Yao and K. R. Coffey, Journal of Electron Microscopy, Vol. 57, no., 2, p. 47-52, 2008.
  24. "The influence of periodicity on the structure and properties of annealed [Fe/Pt]n multilayer films," B. Yao and K. R. Coffey, Journal of Magnetism and Magnetic Materials, vol. 320, no. 3-4, p. 559-564, 2008.
  25. " Comparison of the Work Function of Pt-Ru Binary Metal Alloys Extracted from MOS Capacitor and Schottky Barrier Diode",R. M. Todi, M. S. Erickson, K. B. Sundaram, K. Barmak, K. R. Coffey, IEEE Transactions on Electron Devices, vol. 54, no. 4, p. 807-813, 2007.
  26. "A Modified Back-etch Method for Preparation of Plan View High Resolution Transmission Electron Microscopy Samples," B. Yao, R.V. Petrova, R.R. Vanfleet, K.R. Coffey, Journal of Electron Microscopy, Vol. 55, Issue 4, pages 209-214, 2006.
  27. "Characterization of Pt–Ru Binary Alloy Thin Films for Work Function Tuning," R. M. Todi, K. B. Sundaram, K. R. Coffey, IEEE Electron Device Letters, Vol. 27, Issue 7, pages 542-545, 2006.
  28. "X-ray photoelectron spectroscopy analysis of oxygen annealed radio frequency sputter deposited SiCN thin films," R. M. Todi, K. B. Sundaram, K. R. Coffey, Journal of the Electrochemical Society, Vol. 153, issue 7, pages G640-G643, 2006.
  29. "Compositional stability of FePt nanoparticles on SiO2/Si during annealing", B. Yao, R. V. Petrova, R. R. Vanfleet, V. Lam, and K.R. Coffey, Journal of Applied Physics, Vol. 99, Issue 8, Article No. 08E913, 2006.
  30. "Experimental study of the interaction of laser radiation with silver nanoparticles in SiO2 matrix," M. Sendova, M. Sendova-Vassileva, J. C. Pivin, H. Hofmeister, K. Coffey, A. Warren,Journal of Nanoscience and Nanotechnology, Vol. 6, Issue 3, pages 748-755, 2006.
  31. "Characterization of Individual L10 FePt Nanoparticles," R. V. Petrova, R. R. Vanfleet, D. Richardson, B. Yao, and K. R. Coffey, IEEE Transactions on Magnetics, vol. 41, Issue 10, pages 3202-3204, 2005.
  32. "On the relationship of magnetocrystalline anisotropy and stoichiometry in epitaxial L1(0) CoPt (001) and FePt (001) thin films," K. Barmak, J. Kim, K. R. Coffey, M. F. Toney, A. J. Kellock, J.-U. Thiele, Journal of Applied Physics, Vol. 98, Issue 3, Article 033904, Aug. 2005.
  33. "Comparison of the agglomeration behavior of thin metallic films on SiO2," P. R. Gadkari, A. P. Warren, R. M. Todi, R. V. Petrova, and K. R. Coffey, Journal of Vacuum Science and Technology A, Vol. 23, Issue 4, pp. 1152-1161, Jul.-Aug. 2005.
  34. "Growth and characterization of sputtered BSTO/BaM multilayers," S. Srinath, N. A. Frey, R. Heindl, H. Srikanth, K. R. Coffey, and N. J. Dudney,Journal of Applied Physics, Vol. 97, Issue 10, Article 10J115, May 2005.
  35. "Temperature dependence of the magnetization reversal of thin film longitudinal magnetic recording media," K.R. Coffey, J.-U. Thiele, and T. Thomson, IEEE Transactions on Magnetics, Vol. 40, Issue 4, pp. 2440-2442, July 2004.
  36. "Stoichiometry-anisotropy connections in epitaxial FePt(001) films," K. Barmak, J. Kim, L. H. Lewis, K. R. Coffey, M. F. Toney, A. J. Kellock, and J.-U. Thiele,Journal of Applied Physics, Vol. 95, Issue 11, part 2, pp. 7501-7503, June 2004.
  37. "Angle-dependent switching of granular and multilayer perpendicular media," T. Thomson, K. R. Coffey, and J.-U. Thiele, IEEE Transactions on Magnetics, Vol. 39, Issue 5, pp. 2314-2316, Sept. 2003.
  38. "Angle dependent magnetization reversal of thin film magnetic recording media," K. R. Coffey, T. Thomson, and J.-U. Thiele,Journal of Applied Physics, Vol. 93, Issue 10, pp. 8471-8473, May 2003.
  39. "Angular dependence of the switching field of thin film longitudinal and perpendicular magnetic recording media," K. R. Coffey, T. Thomson, and J.-U. Thiele,Journal of Applied Physics, Vol. 92, Issue 8, pp. 4553-4559, Oct. 2002.
  40. "Temperature dependent magnetic properties of highly chemically ordered Fe55-xNixPt45 L10 films," J.-U. Thiele, K. R. Coffey, M.F. Toney, J.A. Hedstrom, and A.J. Kellock, Journal of Applied Physics, Vol. 91, Issue 10, pp. 6595-6600, May 2002.
  41. "Measurement of carbon film thickness by inelastic electron scatter," C. E. Bryson, L. Vasilyev, R. Linder, R. L. White, J.-U. Thiele, K. R. Coffey, and J. H. Brannon, Journal of Vacuum Science and Technology A, vol. 19, no. 5, p. 2695-2697, Sept. 2001