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. Click here to view a larger list of publications.
Direct determination of mode-projected electron-phonon coupling in the time domain
MengXing Na, Arthur K Mills, Fabio Boschini, Matteo Michiardi, Benjamin Nosarzewski, Ryan P Day, Elia Razzoli, Alexander Sheyerman, Michael Schneider, Giorgio Levy, Sergey Zhdanovich, Thomas P Devereaux, Alexander F Kemper, David J Jones, Andrea Damascelli
Science, 366(6470), (2019), 1231-1236, doi:10.1126/science.aaw1662
Spectral Evidence for Emergent Order in Ba1-xNaxFe2As2
M. Yi, A. Frano, D. H. Lu, Y. He, Meng Wang, B. A. Frandsen, A. F. Kemper, R. Yu, Q. Si, L. Wang, M. He, F. Hardy, P. Schweiss, P. Adelmann, T. Wolf, M. Hashimoto, S.-K. Mo, Z. Hussain, M. Le Tacon, A. E. Böhmer, D.-H. Lee, Z.-X. Shen, C. Meingast, and R. J. Birgeneau
Physical Review Letters, 121, (2018), 127001, doi:10.1103/PhysRevLett.121.127001
Theoretical phase diagram for the room temperature Electron-Hole Liquid in photo-excited quasi-2D monolayer MoS2.
A. Rustagi and A.F. Kemper
Nano Letters 18, 1, (2017), 455-459
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, (2017), 13940
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, (2016), 13761
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, (2016), 13143
Theory of light-enhanced phonon-mediated superconductivity.
M.A. Sentef, A.F. Kemper, A. Georges and C. Kollath
Phys. Rev. B, 93, (2016), 144506
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, (2015), 224517
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, (2014), 075126
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), (2013), 136802
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), (2013), 041033
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, (2012), 838
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), (2011), 6878-6883
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), (2010), 073030