Photo-induced semimetallic states realised in electron–hole coupled insulators

Kozo Okazaki; Yu Ogawa; Takeshi Suzuki; Takashi Yamamoto; Takashi Someya; Shoya Michimae; Mari Watanabe; Yangfan Lu; Minoru Nohara; Hidenori Takagi; Naoyuki Katayama; Hiroshi Sawa; Masami Fujisawa; Teruto Kanai; Nobuhisa Ishii; Jiro Itatani; Takashi Mizokawa; Shik Shin

doi:10.1038/s41467-018-06801-1

Photo-induced semimetallic states realised in electron–hole coupled insulators

Kozo Okazaki^*, Yu Ogawa, Takeshi Suzuki, Takashi Yamamoto, Takashi Someya, Shoya Michimae, Mari Watanabe, Yangfan Lu, Minoru Nohara, Hidenori Takagi, Naoyuki Katayama, Hiroshi Sawa, Masami Fujisawa, Teruto Kanai, Nobuhisa Ishii, Jiro Itatani, Takashi Mizokawa, Shik Shin

^*Corresponding author for this work

School of Advanced Science and Engineering

Research output: Contribution to journal › Article › peer-review

59 Citations (Scopus)

Abstract

Using light to manipulate materials into desired states is one of the goals in condensed matter physics, since light control can provide ultrafast and environmentally friendly photonics devices. However, it is generally difficult to realise a photo-induced phase which is not merely a higher entropy phase corresponding to a high-temperature phase at equilibrium. Here, we report realisation of photo-induced insulator-to-metal transitions in Ta₂Ni(Se_1−xS_x)₅ including the excitonic insulator phase using time- and angle-resolved photoemission spectroscopy. From the dynamic properties of the system, we determine that screening of excitonic correlations plays a key role in the timescale of the transition to the metallic phase, which supports the existence of an excitonic insulator phase at equilibrium. The non-equilibrium metallic state observed unexpectedly in the direct-gap excitonic insulator opens up a new avenue to optical band engineering in electron–hole coupled systems.

Original language	English
Article number	4322
Journal	Nature communications
Volume	9
Issue number	1
DOIs	https://doi.org/10.1038/s41467-018-06801-1
Publication status	Published - 2018 Dec 1

ASJC Scopus subject areas

Chemistry(all)
Biochemistry, Genetics and Molecular Biology(all)
Physics and Astronomy(all)

Access to Document

10.1038/s41467-018-06801-1

Cite this

Okazaki, K., Ogawa, Y., Suzuki, T., Yamamoto, T., Someya, T., Michimae, S., Watanabe, M., Lu, Y., Nohara, M., Takagi, H., Katayama, N., Sawa, H., Fujisawa, M., Kanai, T., Ishii, N., Itatani, J., Mizokawa, T., & Shin, S. (2018). Photo-induced semimetallic states realised in electron–hole coupled insulators. Nature communications, 9(1), Article 4322. https://doi.org/10.1038/s41467-018-06801-1

Okazaki, K, Ogawa, Y, Suzuki, T, Yamamoto, T, Someya, T, Michimae, S, Watanabe, M, Lu, Y, Nohara, M, Takagi, H, Katayama, N, Sawa, H, Fujisawa, M, Kanai, T, Ishii, N, Itatani, J, Mizokawa, T & Shin, S 2018, 'Photo-induced semimetallic states realised in electron–hole coupled insulators', Nature communications, vol. 9, no. 1, 4322. https://doi.org/10.1038/s41467-018-06801-1

@article{608f09f8ca5d48929c209011e5036d18,

title = "Photo-induced semimetallic states realised in electron–hole coupled insulators",

abstract = "Using light to manipulate materials into desired states is one of the goals in condensed matter physics, since light control can provide ultrafast and environmentally friendly photonics devices. However, it is generally difficult to realise a photo-induced phase which is not merely a higher entropy phase corresponding to a high-temperature phase at equilibrium. Here, we report realisation of photo-induced insulator-to-metal transitions in Ta2Ni(Se1−xSx)5 including the excitonic insulator phase using time- and angle-resolved photoemission spectroscopy. From the dynamic properties of the system, we determine that screening of excitonic correlations plays a key role in the timescale of the transition to the metallic phase, which supports the existence of an excitonic insulator phase at equilibrium. The non-equilibrium metallic state observed unexpectedly in the direct-gap excitonic insulator opens up a new avenue to optical band engineering in electron–hole coupled systems.",

author = "Kozo Okazaki and Yu Ogawa and Takeshi Suzuki and Takashi Yamamoto and Takashi Someya and Shoya Michimae and Mari Watanabe and Yangfan Lu and Minoru Nohara and Hidenori Takagi and Naoyuki Katayama and Hiroshi Sawa and Masami Fujisawa and Teruto Kanai and Nobuhisa Ishii and Jiro Itatani and Takashi Mizokawa and Shik Shin",

note = "Funding Information: We would like to thank H. Fukuyama and Y. Ohta for valuable discussions and comments. This work was supported by JSPS KAKENHI (Grant nos. JP25220707 and JP26610095) and the Photon and Quantum Basic Research Coordinated Development Programme from the Ministry of Education, Culture, Sports, Science and Technology, Japan. T. Someya acknowledges the JSPS Research Fellowship for Young Scientists. Publisher Copyright: {\textcopyright} 2018, The Author(s).",

year = "2018",

month = dec,

day = "1",

doi = "10.1038/s41467-018-06801-1",

language = "English",

volume = "9",

journal = "Nature communications",

issn = "2041-1723",

publisher = "Nature Publishing Group",

number = "1",

}

TY - JOUR

T1 - Photo-induced semimetallic states realised in electron–hole coupled insulators

AU - Okazaki, Kozo

AU - Ogawa, Yu

AU - Suzuki, Takeshi

AU - Yamamoto, Takashi

AU - Someya, Takashi

AU - Michimae, Shoya

AU - Watanabe, Mari

AU - Lu, Yangfan

AU - Nohara, Minoru

AU - Takagi, Hidenori

AU - Katayama, Naoyuki

AU - Sawa, Hiroshi

AU - Fujisawa, Masami

AU - Kanai, Teruto

AU - Ishii, Nobuhisa

AU - Itatani, Jiro

AU - Mizokawa, Takashi

AU - Shin, Shik

N1 - Funding Information: We would like to thank H. Fukuyama and Y. Ohta for valuable discussions and comments. This work was supported by JSPS KAKENHI (Grant nos. JP25220707 and JP26610095) and the Photon and Quantum Basic Research Coordinated Development Programme from the Ministry of Education, Culture, Sports, Science and Technology, Japan. T. Someya acknowledges the JSPS Research Fellowship for Young Scientists. Publisher Copyright: © 2018, The Author(s).

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Using light to manipulate materials into desired states is one of the goals in condensed matter physics, since light control can provide ultrafast and environmentally friendly photonics devices. However, it is generally difficult to realise a photo-induced phase which is not merely a higher entropy phase corresponding to a high-temperature phase at equilibrium. Here, we report realisation of photo-induced insulator-to-metal transitions in Ta2Ni(Se1−xSx)5 including the excitonic insulator phase using time- and angle-resolved photoemission spectroscopy. From the dynamic properties of the system, we determine that screening of excitonic correlations plays a key role in the timescale of the transition to the metallic phase, which supports the existence of an excitonic insulator phase at equilibrium. The non-equilibrium metallic state observed unexpectedly in the direct-gap excitonic insulator opens up a new avenue to optical band engineering in electron–hole coupled systems.

AB - Using light to manipulate materials into desired states is one of the goals in condensed matter physics, since light control can provide ultrafast and environmentally friendly photonics devices. However, it is generally difficult to realise a photo-induced phase which is not merely a higher entropy phase corresponding to a high-temperature phase at equilibrium. Here, we report realisation of photo-induced insulator-to-metal transitions in Ta2Ni(Se1−xSx)5 including the excitonic insulator phase using time- and angle-resolved photoemission spectroscopy. From the dynamic properties of the system, we determine that screening of excitonic correlations plays a key role in the timescale of the transition to the metallic phase, which supports the existence of an excitonic insulator phase at equilibrium. The non-equilibrium metallic state observed unexpectedly in the direct-gap excitonic insulator opens up a new avenue to optical band engineering in electron–hole coupled systems.

UR - http://www.scopus.com/inward/record.url?scp=85055080304&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85055080304&partnerID=8YFLogxK

U2 - 10.1038/s41467-018-06801-1

DO - 10.1038/s41467-018-06801-1

M3 - Article

C2 - 30333495

AN - SCOPUS:85055080304

SN - 2041-1723

VL - 9

JO - Nature communications

JF - Nature communications

IS - 1

M1 - 4322

ER -

Photo-induced semimetallic states realised in electron–hole coupled insulators

Abstract

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this