Abstract

Charge acceleration during an intense light field application to solids attracts much attention as elementary processes in high-harmonic generation and photoelectron emission. For manipulating such attosecond dynamics of charge, carrier-envelope-phase (CEP: relative phase between carrier oscillation of light field and its envelope function) control has been employed in insulators, nanometal and graphene. In superconducting materials, collective control of charge motion is expected because of its strongly coherent nature of quasi-particles. Here we report that, in a layered organic superconductor, a non-linear petahertz current driven by a single-cycle 6 femtosecond near infrared field shows up as second harmonic generation (SHG), which is in contrast to the common belief that even harmonics are forbidden in the centrosymmetric system. The SHG represents a CEP sensitive nature and an enhancement near the superconducting temperature. The result and its quantum many-body analysis indicate that a polarized current is induced by non-linear acceleration of charge, which is amplified by superconducting fluctuations. This will lead to petahertz functions of superconductors and of strongly correlated systems.

Here the authors show second harmonic generation (SHG) from a centrosymmetric organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br. They find unusual temperature dependence and CEP-sensitive nature of the SHG which are explained in terms of nonlinear current.

Details

Title
Petahertz non-linear current in a centrosymmetric organic superconductor
Author
Kawakami, Y 1 ; Amano, T 1 ; Ohashi, H 1 ; Itoh, H 1 ; Nakamura, Y 2 ; Kishida, H 2 ; Sasaki, T 3   VIAFID ORCID Logo  ; Kawaguchi, G 4 ; Yamamoto, H M 4   VIAFID ORCID Logo  ; Yamamoto, K 5 ; Ishihara, S 1 ; Yonemitsu, K 6 ; Iwai, S 1   VIAFID ORCID Logo 

 Tohoku University, Department of Physics, Sendai, Japan (GRID:grid.69566.3a) (ISNI:0000 0001 2248 6943) 
 Nagoya University, Department of Applied Physics, Nagoya, Japan (GRID:grid.27476.30) (ISNI:0000 0001 0943 978X) 
 Tohoku University, Institute for Materials Research, Sendai, Japan (GRID:grid.69566.3a) (ISNI:0000 0001 2248 6943) 
 Institute for Molecular Science, Okazaki, Japan (GRID:grid.467196.b) (ISNI:0000 0001 2285 6123) 
 Okayama University of Science, Department of Applied Physics, Okayama, Japan (GRID:grid.444568.f) (ISNI:0000 0001 0672 2184) 
 Chuo University, Department of Physics, Tokyo, Japan (GRID:grid.443595.a) (ISNI:0000 0001 2323 0843) 
Publication year
2020
Publication date
2020
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2435011254
Copyright
© The Author(s) 2020. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.