Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse
In this paper, we present a novel theoretical approach, which allows the study of nonequilibrium dynamics of both electrons and atoms/ions within free-electron laser excited semiconductors at femtosecond time scales. The approach consists of the Monte-Carlo method treating photoabsorption, high-ener...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2013-01-01
|
| Series: | New Journal of Physics |
| Online Access: | https://doi.org/10.1088/1367-2630/15/1/015016 |
| _version_ | 1797751821429637120 |
|---|---|
| author | Nikita Medvedev Harald O Jeschke Beata Ziaja |
| author_facet | Nikita Medvedev Harald O Jeschke Beata Ziaja |
| author_sort | Nikita Medvedev |
| collection | DOAJ |
| description | In this paper, we present a novel theoretical approach, which allows the study of nonequilibrium dynamics of both electrons and atoms/ions within free-electron laser excited semiconductors at femtosecond time scales. The approach consists of the Monte-Carlo method treating photoabsorption, high-energy-electron and core-hole kinetics and relaxation processes. Low-energy electrons localized within the valence and conduction bands of the target are treated with a temperature equation, including source terms, defined by the exchange of energy and particles with high-energy electrons and atoms. We follow the atomic motion with the molecular dynamics method on the changing potential energy surface. The changes of the potential energy surface and of the electron band structure are calculated at each time step with the help of the tight-binding method. Such a combination of methods enables investigation of nonequilibrium structural changes within materials under extreme ultraviolet (XUV) femtosecond irradiation. Our analysis performed for diamond irradiated with an XUV femtosecond laser pulse predicts for the first time in this wavelength regime the nonthermal phase transition from diamond to graphite. Similar to the case of visible light irradiation, this transition takes place within a few tens of femtoseconds and is caused by changes of the interatomic potential induced by ultrafast electronic excitations. It thus occurs well before the heating stimulated by electron–phonon coupling starts to play a role. This allows us to conclude that this transition is nonthermal and represents a general mechanism of the response of solids to ultrafast electron excitations. |
| first_indexed | 2024-03-12T16:54:10Z |
| format | Article |
| id | doaj.art-efcc16588aef47af907ba2995acf072e |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:54:10Z |
| publishDate | 2013-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-efcc16588aef47af907ba2995acf072e2023-08-08T11:03:45ZengIOP PublishingNew Journal of Physics1367-26302013-01-0115101501610.1088/1367-2630/15/1/015016Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulseNikita Medvedev0Harald O Jeschke1Beata Ziaja2Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, GermanyInstitut für Theoretische Physik, Goethe-Universität Frankfurt am Main , Max-von-Laue-Strasse 1, D-60438 Frankfurt, GermanyCenter for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany; Institute of Nuclear Physics , Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, PolandIn this paper, we present a novel theoretical approach, which allows the study of nonequilibrium dynamics of both electrons and atoms/ions within free-electron laser excited semiconductors at femtosecond time scales. The approach consists of the Monte-Carlo method treating photoabsorption, high-energy-electron and core-hole kinetics and relaxation processes. Low-energy electrons localized within the valence and conduction bands of the target are treated with a temperature equation, including source terms, defined by the exchange of energy and particles with high-energy electrons and atoms. We follow the atomic motion with the molecular dynamics method on the changing potential energy surface. The changes of the potential energy surface and of the electron band structure are calculated at each time step with the help of the tight-binding method. Such a combination of methods enables investigation of nonequilibrium structural changes within materials under extreme ultraviolet (XUV) femtosecond irradiation. Our analysis performed for diamond irradiated with an XUV femtosecond laser pulse predicts for the first time in this wavelength regime the nonthermal phase transition from diamond to graphite. Similar to the case of visible light irradiation, this transition takes place within a few tens of femtoseconds and is caused by changes of the interatomic potential induced by ultrafast electronic excitations. It thus occurs well before the heating stimulated by electron–phonon coupling starts to play a role. This allows us to conclude that this transition is nonthermal and represents a general mechanism of the response of solids to ultrafast electron excitations.https://doi.org/10.1088/1367-2630/15/1/015016 |
| spellingShingle | Nikita Medvedev Harald O Jeschke Beata Ziaja Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse New Journal of Physics |
| title | Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| title_full | Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| title_fullStr | Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| title_full_unstemmed | Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| title_short | Nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| title_sort | nonthermal phase transitions in semiconductors induced by a femtosecond extreme ultraviolet laser pulse |
| url | https://doi.org/10.1088/1367-2630/15/1/015016 |
| work_keys_str_mv | AT nikitamedvedev nonthermalphasetransitionsinsemiconductorsinducedbyafemtosecondextremeultravioletlaserpulse AT haraldojeschke nonthermalphasetransitionsinsemiconductorsinducedbyafemtosecondextremeultravioletlaserpulse AT beataziaja nonthermalphasetransitionsinsemiconductorsinducedbyafemtosecondextremeultravioletlaserpulse |