Universität zu Köln

Murotani, Yuta, Takayama, Masayuki, Sekiguchi, Fumiya, Kim, Changsu, Akiyama, Hidefumi and Shimano, Ryo (2018). Terahertz field-induced ionization and perturbed free induction decay of excitons in bulk GaAs. J. Phys. D-Appl. Phys., 51 (11). BRISTOL: IOP PUBLISHING LTD. ISSN 1361-6463

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Abstract

We investigated the interaction between an intense terahertz (THz) pulse and excitons in bulk GaAs by using THz pump near-infrared (NIR) optical probe spectroscopy. We observed a clear spectral oscillation in the NIR transient absorption spectra at low temperature, which is interpreted as the THz pump-induced perturbed free induction decay (PFID) of the excitonic interband polarization. We performed a numerical simulation based on a microscopic theory and identified that the observed PFID signal originates from the THz field-induced ionization of excitons. Using a real-space representation of the excitonic wave function, we visualized how the ionization of an exciton proceeds under the intense single-cycle THz electric field. We also calculated the nonlinear susceptibility with the lowest-order perturbation theory assuming a weak THz pump, which showed a similar spectral feature with that obtained by the full treatment to field-induced ionization process. This coincidence is attributed to the fact that 1s-excitonic interband polarization is modified predominantly through interactions with the p-wave component of the excitonic wave function. A simple phenomenological expression of the PFID signal is presented to discuss effects of the THz pump pulse duration on the spectral oscillation.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Murotani, Yuta UNSPECIFIED UNSPECIFIED UNSPECIFIED Takayama, Masayuki UNSPECIFIED UNSPECIFIED UNSPECIFIED Sekiguchi, Fumiya UNSPECIFIED UNSPECIFIED UNSPECIFIED Kim, Changsu UNSPECIFIED UNSPECIFIED UNSPECIFIED Akiyama, Hidefumi UNSPECIFIED UNSPECIFIED UNSPECIFIED Shimano, Ryo UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-192569
DOI:	10.1088/1361-6463/aaa989
Journal or Publication Title:	J. Phys. D-Appl. Phys.
Volume:	51
Number:	11
Date:	2018
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1361-6463
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TRANSIENT OSCILLATIONS; COHERENT TRANSIENTS; FEMTOSECOND; GENERATION Multiple languages Physics, Applied Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/19256