Observation of anomalous electron relaxation in optically excited 1<i>T</i>-TaSe<sub>2</sub>

Bulletin of the American Physical Society

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APS March Meeting 2019

Volume 64, Number 2

Monday–Friday, March 4–8, 2019; Boston, Massachusetts

Session E06: Electronic States in Se Chalcogenides: Including Excitonic Behavior

8:00 AM–10:48 AM, Tuesday, March 5, 2019
BCEC Room: 109A

Sponsoring Unit: DCMP
Chair: Johnpierre Paglione, University of Maryland, College Park

Abstract: E06.00006 : Observation of anomalous electron relaxation in optically excited 1T-TaSe₂

9:00 AM–9:12 AM

Abstract

Presenter:

Yingchao Zhang
(Department of Physics and JILA, University of Colorado, Boulder)

Authors:

Yingchao Zhang
(Department of Physics and JILA, University of Colorado, Boulder)

Xun Shi
(Department of Physics and JILA, University of Colorado, Boulder)

Wenjing You
(Department of Physics and JILA, University of Colorado, Boulder)

Zhensheng Tao
(Department of Physics and JILA, University of Colorado, Boulder)

Kai Rossnagel
(Institute of Experimental and Applied Physics, Kiel University)

Michael Bauer
(Institute of Experimental and Applied Physics, Kiel University)

Henry C Kapteyn
(Department of Physics and JILA, University of Colorado, Boulder)

Margaret Mary Murnane
(Department of Physics and JILA, University of Colorado, Boulder)

Ultrafast light pulses can drive materials far from their equilibrium states and is a powerful approach for manipulating their states. The resultant multi-step energy and momentum relaxation processes can give us insight into the dominant interactions in these materials. In this work, we present a series of anomalous behaviors observed in the electron relaxation in the charge density wave (CDW) material 1T-TaSe₂. After exciting the material with a femtosecond laser pulse, we measure the temporal evolution of the band structure and electron temperature. We observe a band oscillation that is coherently coupled to the CDW amplitude mode. Meanwhile, the hot electron temperature relaxes anomalously fast, and very different from that predicted by the widely-used N-temperature model. Moreover, this anomaly shows a critical change at the laser fluence corresponding to the ultrafast phase transformation to a new long-lived metastable state. These results offer a rare opportunity for better understanding of the coherent electron-phonon coupling.

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Bulletin of the American Physical Society

APS March Meeting 2019

Volume 64, Number 2

Monday–Friday, March 4–8, 2019; Boston, Massachusetts

Session E06: Electronic States in Se Chalcogenides: Including Excitonic Behavior

Abstract: E06.00006 : Observation of anomalous electron relaxation in optically excited 1T-TaSe2

Presenter:

Authors:

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Abstract: E06.00006 : Observation of anomalous electron relaxation in optically excited 1T-TaSe₂