American Physical Society
SrMnSb2 is a candidate Dirac semimetal whose electrons near the Y point have the linear dispersion and low mass of a Dirac cone. Here we demonstrate that ultrafast, 800-nm optical pulses can launch coherent phonon oscillations in Sr0.94Mn0.92Sb2, particularly an Ag mode at 4.4 THz. Through first-principles calculations of the electronic and phononic structure of SrMnSb2, we show that high-amplitude oscillations of this mode would displace the atoms in a way that transiently opens and closes a gap at the node of the Dirac cone. The ability to control the nodal gap on a subpicosecond timescale could create opportunities for the design and manipulation of Dirac fermions.
C. P. Weber, M. G. Masten, T. C. Ogloza, B. S. Berggren, M. K. L. Man, K. M. Dani, J. Liu, Z. Mao, D. D. Klug, A. A. Adeleke, and Y. Yao, “Using coherent phonons for ultrafast control of the Dirac node of SrMnSb2”, Phys. Rev. B 98 155115 (2018). https://journals.aps.org/prb/ abstract/10.1103/PhysRevB.98.155115