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Pump-Probe Spectroscopy probing ultrafast and ultrasmall..


We are in the process of designing a novel ultrafast ARPES spectrometer...

The new design is based on our past experience with spectroscopic studies of quantum matter (some relevant papers and backgroud materials are available here):

Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface

Online results at KITP (2007-2008) :

KITP Proc. (2007)

KITP Proc. (2008)

For ultrafast studies: Theoretical discovery of Weyl semimetal class TaAs (PhysicsWorld 2015)

Topologically protected Single Dirac Cone (Spin-Textured)
Nature Physics
With the discovery of Bi-based topological insulators (KITP-2007 and KITP-2008) ultrafast/time-resolved ARPES study gained significant momentum in general. Some of the recents results are here:

Phys. Rev. Lett. (2015)

"Topological Insulators" and "Weyl Semimetals" highlighted by NATURE's Insight on
Quantum Materials

along with superconductivity and spin liquids.
A related paper is also listed in NATURE's editorial collection of articles related to 2016 Nobel Prize in Physics.

Some recent results:
Gigantic surface life-time of an intrinsic topological insulator
(revealed via time-resolved pump-probe ARPES)

M. Neupane, S.-Y. Xu, Y. Ishida, et al.;

Phys. Rev. Lett. 115, 116801 (2015)

Electronic structure and relaxation dynamics in a superconducting topological material
(via time-resolved ARPES)
M. Neupane, Y. Ishida, R. Sankar, J.-X. Zhu, D. S. Sanchez, I. Belopolski, S.-Y. Xu, N. Alidoust, M. M. Hosen, S. Shin, F. Chou, M. Z. Hasan,

Scientific Reports 6:22557 (2016)

Experimental signatures of phase interference and sub-femtosecond time dynamics on the incident energy axis of resonant inelastic x-ray scattering
L. Andrew Wray, S.-W. Huang, Y. Xia,

Phys. Rev. B 91, 035131 (2015)

Tuning a Schottky barrier in a photoexcited topological insulator with transient Dirac cone electron-hole asymmetry
(time-resolved (pump-probe) ARPES)
M. Hajlaoui, E. Papalazarou, J. Mauchain, et al.;

Nature Commun. 5, 3003 (2014)

Signatures of a time-reversal symmetric Weyl semimetal with only four Weyl points
via time-resolved (pump-probe) ARPES
Ilya Belopolski, Peng Yu, Daniel S. Sanchez, Yukiaki Ishida, Tay-Rong Chang, Songtian S. Zhang, Su-Yang Xu, Hao Zheng, Guoqing Chang, Guang Bian, Horng-Tay Jeng, Takeshi Kondo, Hsin Lin, Zheng Liu, Shik Shin & M. Zahid Hasan

Nature Commun. 8, 942 (2017)


Frontiers of Ultrafast X-ray science (DOE Report) ..

Front page: Nature Materials FOCUS issue on "Topological Semimetals" ..

Next generation ultrafast spectrometer under development ...