Center for Integrated Nanotechnologies

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Rohit Prativadi Prasankumar

Rohit Prasankumar

Email
Phone (505) 284-7966

Capabilities

  • CINT
  • Property Measurements

Expertise

Ultrafast dynamics and phenomena in complex materials from terahertz to x-ray frequencies , including:

  • Complex oxides and oxide heterostructures (e.g., superconductors, manganites, and multiferroics)
  • Heavy fermion materials
  • Semiconductor nanostructures (particularly nanowires and quantum dots)
  • Two-dimensional nanosystems (e.g., graphene, topological insulators, and transition metal dichalcogenides)
  • Metamaterials and plasmonic devices
  • Organic and photovoltaic materials

Education

Ph.D., Electrical Engineering, Massachusetts Institute of Technology, May 2003

Thesis title: Development and Application of Saturable Absorbers to Femtosecond Solid-State Laser Mode-Locking

Advisor: Professor James G. Fujimoto

M. S., Electrical Engineering, Massachusetts Institute of Technology, September 1999

Thesis title: Novel Saturable Absorber Devices Grown Using RF and Magnetron RF Sputtering

B. S., Electrical Engineering, University of Texas at Austin, May 1997 (graduated magna cum laude)

Advisor: Professor Rebecca Richards-Kortum

 

Professional Appointments

Technical Staff Member, Laboratory for Ultrafast Materials and Optical Science (LUMOS), Center for Integrated Nanotechnologies (CINT), February 2006 - present

Acting Partner Scientific Leader, Nanophotonics Thrust (CINT), June 2009 - March 2010

Postdoctoral Researcher, LUMOS, MST-10 August 2003 - February 2006

 

Professional Societies

American Physical Society

Optical Society of America

 

Awards

  • Ernest and Virginia Cockrell Scholarship, University of Texas at Austin (1993-1997)
  • National Merit Scholarship (1993-1997)                                                                                 
  • One of ~20 students nationwide selected to attend the Lawrence Livermore Undergraduate Summer Institute for Applied Science (1996)
  • NSF Graduate Fellowship, Honorable Mention (1997)
  • I2CAM Junior Travel Award to attend Gordon Conference on Ultrafast Techniques (2008)
 

Publications

Books and Book Chapters:

1. “Optical Techniques for Materials Characterization,” edited by R. P. Prasankumar and A. J. Taylor, Taylor & Francis (2011). 

2. "Emerging Optical Techniques for Characterizing Complex Materials," R. P. Prasankumar and A. J. Taylor, in Optical Techniques for Materials Characterization, Taylor & Francis (2011).

Selected Publications (complete list at https://scholar.google.com/citations?view_op=list_works&hl=en&user=B24hpogAAAAJ):

  1. J. Lee, S. A. Trugman, C. L. Zhang, X. S. Xu, S.-W. Cheong, C. D. Batista, D. A. Yarotski, A. J. Taylor, and R. P. Prasankumar, “Using ultrafast optical spectroscopy to reveal antipolar bilayer stacking in LuFe2O4 through the influence of charge ordering on acoustic phonon oscillations,” Appl. Phys. Lett. 107, 042906 (2015). 
  2. P. C. Upadhya, J. A. Martinez, Q. Li, G. T. Wang, B. S. Swartzentruber, A. J. Taylor, and R. P. Prasankumar, “Space-and-time-resolved spectroscopy of single GaN nanowires”, Appl. Phys. Lett. 106, 263103 (2015). 
  3. N. Kamaraju, W. Pan, U. Ekenberg, D. M. Gvozdic, S. Boubanga-Tombet, P. C. Upadhya, J. Reno, A. J. Taylor, and R. P. Prasankumar, “Terahertz magneto-optical spectroscopy of a two-dimensional hole gas,” Appl. Phys. Lett. 106, 031902 (2015) 
  4. Y.-M. Sheu, S. A. Trugman, L. Yan, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, “Ultrafast all-optical manipulation of interfacial-magnetoelectric coupling,” Nature Communications 5, 5832 (2014).
  5. Y. M Sheu, S. A. Trugman, L. Yan, J. Qi, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, “Polaronic nature of competing interfacial ferromagnetic/antiferromagnetic order in a La0.7Ca0.3MnO3/BiFeO3 heterostructure,” Phys. Rev. X 4, 021001 (2014).
  6. K. Appavoo, N. F. Brady, B. Wang, M. A. Seo, J. Nag, R. P. Prasankumar, S. T. Pantelides, D. J. Hilton, and R. F. Haglund, Jr., “Ultrafast phase transition via catastrophic phonon collapse driven by plasmonic electron injection,” Nano Lett. 14, 1127 (2014).
  7. J. Qi, T. Durakiewicz, S. A. Trugman, J.-X. Zhu, P. S. Riseborough, R. Baumbach, E. D. Bauer, K. Gofryk, J.-Q. Meng, J. J. Joyce, A. J. Taylor,, and R. P. Prasankumar, “Revealing multiple gaps in the electronic structure of USb2 using femtosecond optical pulses”, Phys. Rev. Lett. 111, 057402 (2013).
  8. Y.-M. Sheu, S. A. Trugman, L. Yan, C.-P. Chuu, Z. Bi, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, “Photo-induced stabilization and enhancement of the ferroelectric polarization in Ba0.1Sr0.9TiO3/La0.7Ca(Sr)0.3MnO3 thin film heterostructures,” Phys. Rev. B (Rapid Comm.) 88, 020101(R) (2013)
  9. M. A. Seo, S. Boubanga-Tombet, J. Yoo, Z. Ku, A. V. Gin, S. T. Picraux, S. R. J. Brueck, A. J. Taylor, and R. P. Prasankumar, “Ultrafast optical wide field microscopy,” Optics Express 21, 8763 (2013).
  10. M. A. Seo, J. Yoo, S. A. Dayeh, S. T. Picraux, A. J. Taylor, and R. P. Prasankumar, “Mapping carrier diffusion in single silicon core-shell nanowires with ultrafast optical microscopy,” Nano Lett. 12, 6334 (2012).
  11. Y.-M. Sheu, S. A. Trugman, Y.-S. Park, S. Lee, H. Y. Yi, S.-W. Cheong, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, “Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO3,” Appl. Phys. Lett. 100, 242904 (2012).
  12. K. M. Dani*, J. Lee*, R. Sharma, A. D. Mohite, C. M. Galande. P. M. Ajayan, A. M. Dattelbaum, H. Htoon, A. J. Taylor, and R. P. Prasankumar, “Intraband conductivity response in graphene observed using ultrafast infrared-pump visible-probe spectroscopy,” Phys. Rev. B 86, 125403 (2012).
  13. M. A. Seo, S. A. Dayeh, P. C. Upadhya, J. Martinez, B. S. Swartzentruber, S. T. Picraux, A. J. Taylor, and R. P. Prasankumar, “Understanding ultrafast carrier dynamics in single quasi-one-dimensional Si nanowires,” Appl. Phys. Lett. 100, 071104 (2012).
  14. P. C. Upadhya, Q. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” (invited) Semiconductor Science and Technology (special issue on nanowires), 25, 024017 (2010).
  15. R. P. Prasankumar, Prashanth C. Upadhya, and A. J. Taylor, “Ultrafast carrier dynamics in semiconductor nanowires,” invited review paper, Physica Status Solidi (b), 246, 1973 (2009).
  16. K. M. Dani, Z. Ku, P. C. Upadhya, R. P. Prasankumar, S. R. J. Brueck, and A. J. Taylor, “Sub-picosecond optical switching with a negative index metamaterial,” Nano Letters 9, 3565 (2009).
  17. R. P. Prasankumar, S. G. Choi, S. A. Trugman, S. T. Picraux, and A. J. Taylor, “Ultrafast electron and hole dynamics in germanium nanowires,” Nano Letters 8, 1619 (2008).
  18. R. P. Prasankumar, R. S. Attaluri, R. D. Averitt, J. Urayama, N. Weisse-Bernstein, P. Rotella, A. Stintz, S. Krishna, and A. J. Taylor, “Ultrafast carrier dynamics in an InAs/InGaAs quantum-dots-in-a-well heterostructure,” Optics Express, 16, 1165 (2008).
  19. D. J. Hilton, R. P. Prasankumar, et al, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99, 226401 (2007).
  20. D. J. Hilton*, R. P. Prasankumar*, S. A. Trugman, A. J. Taylor, and R. D. Averitt, “On photo-induced phenomena in complex materials: Probing quasiparticle dynamics using infrared and far-infrared pulses,” invited review article, Journal of the Physical Society of Japan 75, 011006 (2006).
  21. R. P. Prasankumar, H. Okamura, H. Imai, Y. Shimakawa, Y. Kubo, S. A. Trugman, A. J. Taylor, and R. D. Averitt, “Coupled charge-spin dynamics in the magnetoresistive pyrochlore Tl2Mn2O7 probed using ultrafast midinfrared spectroscopy,” Physical Review Letters 95, 267404 (2005).
  22. R. P. Prasankumar, A. Scopatz, D. J. Hilton, A. J. Taylor, R. D. Averitt, J. Zide, and A. C. Gossard, “Carrier dynamics in self-assembled ErAs nanoislands embedded in GaAs measured by optical pump-THz probe spectroscopy,” Applied Physics Letters 86, 201105 (2005).
  23. Rohit P. Prasankumar, Ingmar Hartl, Juliet T. Gopinath, Erich P. Ippen, James G. Fujimoto, Paul Mak, and Michael F. Ruane, “Design and characterization of semiconductor-doped silica film saturable absorbers,” Journal of the Optical Society of America B 21, 851 (2004).
  24. R. P. Prasankumar, Y. Hirakawa, A. M. Kowalewicz Jr., F. X. Kärtner, J. G. Fujimoto, and W. H. Knox, “An extended cavity femtosecond Cr:LiSAF laser pumped by low cost diode lasers,” Optics Express 11, 1265 (2003).
  25. R. P. Prasankumar, C. Chudoba, J. G. Fujimoto, P. Mak, and M. F. Ruane, “Self-starting mode locking in a Cr:forsterite laser using non-epitaxially grown semiconductor-doped silica films,” Optics Letters 27, 1564 (2002).

Selected Recent Invited Presentations:

  1. R. P. Prasankumar, “Ultrafast Science: Quicker than the Blink of an Eye,” presented at TEDxLANL, 2015. 
  2. R. P. Prasankumar, “Taming the nanoscale to go beyond the limits of nature,” presented at TEDxABQ salon-Technology, 2014.
  3. M. A. Seo, J. Yoo, S. A. Dayeh, S. T. Picraux, A. J. Taylor, and R. P. Prasankumar, “Tracking charge carriers through space and time in single silicon core-shell nanowires,” presented at the MRS Fall Meeting, 2014.
  4. M. A. Seo, J. Yoo, S. A. Dayeh, S. T. Picraux, A. J. Taylor, and R. P. Prasankumar, “Mapping carrier diffusion in single silicon core-shell nanowires with ultrafast optical microscopy,” presented at ICMAT-2013, 2013.
  5. R. P. Prasankumar, “Unraveling the Interplay between Electric and Magnetic Order in Multiferroic Oxides,” presented at Materials Science & Technology, 2012.