Staff Scientist & Group Lead, Scattering
Photon Science Operations
I am a staff scientist at the ALS responsible for Coherent X-ray Science beamline. I am responsible for the coherent x-ray scattering program at the ALS. I make sure users get to do experiments in a safe environment. to My research is in the emerging area of topological magnetic phenomenon at materials surface/interface, equilibrium and driven magnetization dynamics using resonant x-ray magnetic scattering and x-ray photon correlation spectroscopy (XPCS).
I use synchrotron based resonantly tuned coherent x-ray magnetic scattering to study complex multifunctional materials that are relevant to future technologies and energy efficient devices. These studies unravel new topological phases and provide insight into spontaneous nanoscale fluctuations of order parameters that often form the basis of functionality. These comprehensive studies allow me to atomically probe bulk and interfacial electronic structure and spin texture that provide fundamental insight into the mechanism by which the magnetic interactions takes place. Together with x-ray free electron sources (LCLS) and upcoming diffraction limited synchrotron sources, coherent x-rays will be an important probe for studying condensed matter system.
- J. C. T Lee, J. J. Chess, S. A. Montoya, X. Shi, N. Tamura, S. K. Mishra, P. Fischer, B. J. McMorran, S. K. Sinha, E. E. Fullerton, S. D. Kevan, and S. Roy, Synthesizing skyrmion bound pairs in Fe-Gd thin films, Appl. Phys. Lett.109, 022402 (2016).
- C. Langner, S. Roy, S. K. Mishra, J. C. T. Lee, X.W. Shi, M. A. Hossain, Y.-D. Chuang, S. Seki, Y. Tokura, S. D. Kevan, and R.W. Schoenlein, “Coupled Skyrmion Sublattices in Cu2OSeO3”, Phys. Rev. Lett. 112, 167202 (2014) (First observation of skyrmions with x-rays).
- -W. Chen, H. Guo, K.A. Seu, K. Dumesnil, S. Roy and S.K. Sinha, “Jamming Behavior of Domains in a Spiral Antiferromagnetic System,” Phys. Rev. Lett. 110, 217201 (2013). (Featured on PRL cover)
- Roy, D. Parks, K. A. Seu, E. H. Anderson, S. Cabrini and S. D. Kevan, “Lenseless X-ray imaging in reflection geometry”, Nature Photonics 5, 243 (2011).
- Roy, M. R. Fitzsimmons, S. Park, M. Dorn, O. Petracic, I. V. Roshchin Z. Li, X. Batlle, R. Morales, A. Misra, X. Zhang, K. Chesnel, J. B. Kortright, S. K. Sinha and Ivan. K. Schuller, “Depth profile of uncompensated spins in an antiferromagnetic layer of an exchange bias”. Phys. Rev. Lett. 95, 047201 (2005).
- S. Roy, I S. Dubenko, M. Khan, E. M. Condon, J. Craig, N Ali, B. S. Mitchell and W. Liu, “Magnetic Properties of Perovskite Derived Air Synthesized RBaCo2O5+d (R = La-Ho) Compounds”, Phys. Rev. B 71, 024419 (2005).