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Optical activity in Ge2Sb2Te5 (GST)

Optical activity in Ge2Sb2Te5 (GST)
Optical activity in Ge2Sb2Te5 (GST)
Ge2Sb2Te5 (GST) is an established phase-change material that undergoes fast reversible transitions between amorphous and crystalline states with a high electro-optical contrast, enabling applications in non-volatile optical and electronic memories and optically-switchable structured metamaterials. We have recently demonstrated that optical activity can be induced in pure and doped GST thin films using polarised light, opening up the possibility of controlled induction of anisotropic phase transition in these and related materials for optoelectronic and photonic applications. While the phase transition has generally been understood to proceed via a thermal mechanism, our work strongly suggests that there is an electronic component of crystallization induced by the handedness of circularly polarised nanosecond laser pulses. Significant optical activity in the inorganic thin films, measured by circular dichroism spectroscopy at a synchrotron beamline, implies the existence of chiral structures or motifs. Optically active and inactive regions in the film have been studied using electron diffraction and spectroscopic techniques in order to obtain a structural picture that can be correlated to the optical changes observed. We also propose several mechanisms for the observed effects, which may be extended to other material systems and harnessed in photonic or chiroptical applications.
Shanmugam, Janaki
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Borisenko, Konstantin
23873b86-527e-4c56-9eca-7c7d062f35e6
Luers, Andrew
544a3682-da5e-4cbe-a957-e277924d8aab
Ewart, Paul
575952d2-3d2a-41d0-a2fc-4550fe2db03a
Craig, Christopher
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Hewak, Daniel
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Hussain, Rohanah
d46302e5-4734-4f59-9ac1-bc7b1f62693c
Javorfi, Tamas
21773937-7f1b-42e2-b100-520eff1b307f
Siligardi, Giuliano
ebce490a-2faa-4b98-9703-ae0d6f8e46c2
Bosman, Michel
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Kirkland, Angus
fb19e7a4-617b-48a8-9516-38a74ae15073
Shanmugam, Janaki
418f0ad3-62c2-436b-8d61-5227d171a52e
Borisenko, Konstantin
23873b86-527e-4c56-9eca-7c7d062f35e6
Luers, Andrew
544a3682-da5e-4cbe-a957-e277924d8aab
Ewart, Paul
575952d2-3d2a-41d0-a2fc-4550fe2db03a
Craig, Christopher
2328b42b-552e-4a82-941d-45449e952f10
Hewak, Daniel
87c80070-c101-4f7a-914f-4cc3131e3db0
Hussain, Rohanah
d46302e5-4734-4f59-9ac1-bc7b1f62693c
Javorfi, Tamas
21773937-7f1b-42e2-b100-520eff1b307f
Siligardi, Giuliano
ebce490a-2faa-4b98-9703-ae0d6f8e46c2
Bosman, Michel
64754419-0446-427e-9dff-db18ef9dc2bc
Kirkland, Angus
fb19e7a4-617b-48a8-9516-38a74ae15073

Shanmugam, Janaki, Borisenko, Konstantin, Luers, Andrew, Ewart, Paul, Craig, Christopher, Hewak, Daniel, Hussain, Rohanah, Javorfi, Tamas, Siligardi, Giuliano, Bosman, Michel and Kirkland, Angus (2017) Optical activity in Ge2Sb2Te5 (GST). 9th International Conference on Materials for Advanced Technologies, Suntec, Singapore. 18 - 23 Jun 2017. (In Press)

Record type: Conference or Workshop Item (Poster)

Abstract

Ge2Sb2Te5 (GST) is an established phase-change material that undergoes fast reversible transitions between amorphous and crystalline states with a high electro-optical contrast, enabling applications in non-volatile optical and electronic memories and optically-switchable structured metamaterials. We have recently demonstrated that optical activity can be induced in pure and doped GST thin films using polarised light, opening up the possibility of controlled induction of anisotropic phase transition in these and related materials for optoelectronic and photonic applications. While the phase transition has generally been understood to proceed via a thermal mechanism, our work strongly suggests that there is an electronic component of crystallization induced by the handedness of circularly polarised nanosecond laser pulses. Significant optical activity in the inorganic thin films, measured by circular dichroism spectroscopy at a synchrotron beamline, implies the existence of chiral structures or motifs. Optically active and inactive regions in the film have been studied using electron diffraction and spectroscopic techniques in order to obtain a structural picture that can be correlated to the optical changes observed. We also propose several mechanisms for the observed effects, which may be extended to other material systems and harnessed in photonic or chiroptical applications.

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More information

Accepted/In Press date: 22 February 2017
Venue - Dates: 9th International Conference on Materials for Advanced Technologies, Suntec, Singapore, 2017-06-18 - 2017-06-23
Organisations: Optoelectronics Research Centre

Identifiers

Local EPrints ID: 406357
URI: http://eprints.soton.ac.uk/id/eprint/406357
PURE UUID: bf5e277b-bbba-42ee-aff7-7ae6104e794d
ORCID for Christopher Craig: ORCID iD orcid.org/0000-0001-6919-4294
ORCID for Daniel Hewak: ORCID iD orcid.org/0000-0002-2093-5773

Catalogue record

Date deposited: 10 Mar 2017 10:45
Last modified: 25 Mar 2020 01:33

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Contributors

Author: Janaki Shanmugam
Author: Konstantin Borisenko
Author: Andrew Luers
Author: Paul Ewart
Author: Daniel Hewak ORCID iD
Author: Rohanah Hussain
Author: Tamas Javorfi
Author: Giuliano Siligardi
Author: Michel Bosman
Author: Angus Kirkland

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