NC State Physics Logo

 

Alexander Kemper

Assistant Professor

Biography

Dr. Kemper received his PhD in Physics in 2010 from the University of Florida. He spent 2 years as a postdoctoral research at Stanford University and SLAC National Laboratory followed by serving as an Alvarez Fellow at Lawrence Berkeley National Laboratory before joining the faculty at NC State in 2015 as an assistant professor.

During his PhD studies and continuing during his postdoctoral career, he used computational techniques to study the high-Tc cuprate superconductors, and the novel Fe-based superconductors that were discovered in 2006. Using a combination of Density Functional Theory, Quantum Cluster methods and computational modeling he addressed several aspects of the normal and superconducting states in these materials. Of particular note are a study of the gap symmetry in the Fe-based superconductors, as well as a joint experimental-theory paper showing the presence of four-fold symmetry breaking above the ordering temperatures in Co-doped BaFe2As2.

Starting during his postdoctoral career, and continuing now at NC State, he has embarked on a separate research project in non-equilibrium physics of complex materials. Non-equilibrium phenomena are studied experimentally using ultrafast lasers, which perturb the material under study and observing the subsequent dynamics. He has developed a set of software tools that theoretically model the pump-probe process in a variety of systems, which has to the first theoretical examinations of the pump-probe process. This has led to a series of works answering fundamental questions in non-equilibrium physics as well as collaborative works with experimentalists using pump-probe techniques to answer questions in materials physics.

Select Publications | Complete List Of Publications

Creating stable floquet-weyl semimetals by laser-driving of 3d dirac materials
   H. Hubener, M. A. Sentef, U. De Giovannini, A. F. Kemper, and A. Rubio, Nature Communications, 8, 13940, (2017).

Energy dissipation from a correlated system driven out of equilibrium.
   J. D. Rameau, S. Freutel, A. F. Kemper, M. A. Sentef, J. K. Freericks, T. Avigo, M. Ligges, L. Rettig, Y. Yoshida, H. Eisaki, J. Schneeloch, R. D. Zhong, Z. J. Xu, G. U. Gu, P. D. Johnson, and U. Bovensiepen, Nature Communications, 7, 13761, (2016).

Spin-polarized surface resonances accompanying topological surface state formation
   C. Jozwiak, J. A. Sobota, K. Gotlieb, A. F. Kemper, C. R. Rotundu, R. J. Birgeneau, Z. Hussain, D. H. Lee, Z. X. Shen, and A. Lanzara, Nature Communications, 7, 13143, (2016).

Theory of light-enhanced phonon-mediated superconductivity
   M.A. Sentef, A.F. Kemper, A. Georges and C. Kollath., Phys. Rev. B, 93, 144506, (2016).

Thickness-Dependent Coherent Phonon Frequency in Ultrathin FeSe/SrTiO3 Films
   Shuolong Yang, J.A. Sobota, D. Leuenberger, A.F. Kemper, J.J. Lee, F.T. Schmitt, W. Li, R.G. Moore, P.S. Kirchmann, and Z.-X. Shen, Nano Lett., 15 (6), (2015).

Amplitude Mode Oscillations in Pump-probe Photoemission Spectra of Electron-phonon Mediated Superconductors
   A.F. Kemper, M. A. Sentef, B. Moritz, J. K. Freericks, and T. P. Devereaux, Phys. Rev. B, 92, 224517 (2015).

Theory of Floquet Band Formation and Local Pseudospin Textures in Pump-probe Photoemission of Graphene
   MA Sentef, M Claassen, AF Kemper, B Moritz, T Oka, JK Freericks, TP Devereaux, Nature Communications, 6 (2015).

Effect of Dynamical Spectral Weight Redistribution on Effective Interactions in Time-resolved Spectroscopy
   AF Kemper, MA Sentef, B Moritz, JK Freericks, TP Devereaux, Physical Review B, 90, 075126 (2014).

Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2 Se3
   JA Sobota, SL Yang, AF Kemper, JJ Lee, FT Schmitt, W Li, RG Moore, James G Analytis, Ian R Fisher, Patrick S Kirchmann, Thomas P    Devereaux, Z-X Shen, Physical Review Letters 111 (13), 136802 (2013).

Examining Electron-boson Coupling Using Time-resolved Spectroscopy
   M Sentef, AF Kemper, B Moritz, JK Freericks, ZX Shen, TP Devereaux Physical Review X 3 (4), 041033 (2013)

Phase Fluctuations and the Absence of Topological Defects in a Photo-excited Charge-ordered Nickelate
   PS Kirchmann, O Krupin, M Yi, M Langner, N Huse, JS Robinson, Y Chen, SY Zhou, G Coslovich, B Huber, DA Reis, RA Kaindl, RW    Schoenlein, D Doering, P Denes, WF Schlotter, JJ Turner, SL Johnson, M Först, T Sasagawa, YF Kung, AP Sorini, AF Kemper, B Moritz, TP    Devereaux, D-H Lee, ZX Shen, Z Hussain, Nature communications 3, 838 (2012).

Symmetry-breaking Orbital Anisotropy Observed for Detwinned Ba (Fe1-xCox) 2As2 above the Spin Sensity Wave Transition
   M Yi, D Lu, JH Chu, JG Analytis, AP Sorini, AF Kemper, B Moritz, SK Mo, Rob G Moore, Makoto Hashimoto, Wei-Sheng Lee, Zahid Hussain,    Thomas P Devereaux, Ian R Fisher, Zhi-Xun Shen. Proceedings of the National Academy of Sciences 108 (17), 6878-6883 (2011).

Sensitivity of the Superconducting State and Magnetic Susceptibility to Key Aspects of Electronic Structure in Ferropnictides
   AF Kemper, TA Maier, S Graser, HP Cheng, PJ Hirschfeld, DJ Scalapino. New Journal of Physics 12 (7), 073030 (2010).

Click here to view a larger list of publications.