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Structural involvement in the melting of the charge density wave in 1T − TiSe2

DOI: 10.1103/PhysRevResearch.3.013128 DOI Help

Authors: Max Burian (Swiss Light Source) , Michael Porer (Swiss Light Source) , Jose R. L. Mardegan (Swiss Light Source) , Vincent Esposito (Swiss Light Source) , Sergii Parchenko (Swiss Light Source) , Bulat Burganov (ETH Zurich) , Namrata Gurung (ETH Zurich; Paul Scherrer Institute) , Mahesh Ramakrishnan (Swiss Light Source) , Valerio Scagnoli (ETH Zurich; Paul Scherrer Institut) , Hiroki Ueda (Swiss Light Source) , Sonia Francoual (Deutsches Elektronen-Synchrotron DESY) , Federica Fabrizi (Diamond Light Source) , Yoshikazu Tanaka (RIKEN SPring-8 Center) , Tadashi Togashi (RIKEN SPring-8 Center; Japan Synchrotron Radiation Research Institute (JASRI)) , Yuya Kubota (RIKEN SPring-8 Center; Japan Synchrotron Radiation Research Institute (JASRI)) , Makina Yabashi (RIKEN SPring-8 Center; Japan Synchrotron Radiation Research Institute (JASRI)) , Kai Rossnagel (Christian-Albrechts-Universität zu Kiel; Deutsches Elektronen-Synchrotron DESY) , Steven L. Johnson (ETH Zurich; SwissFEL) , Urs Staub (Swiss Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Research , VOL 3

State: Published (Approved)
Published: February 2021
Diamond Proposal Number(s): 15742

Open Access Open Access

Abstract: In this work, we use ultrafast pump-probe nonresonant and resonant x-ray diffraction to track the periodic lattice distortion and the electronic charge density wave in 1 T − TiSe 2 upon optical excitation. We observe a fluence regime in which the periodic lattice deformation is strongly suppressed but the charge density wave related Se 4 p orbital order remains mostly intact. Complete melting of both structural and electronic order occurs four to five times faster than expected from a purely electronic charge-screening process, strongly suggesting a structurally assisted weakening of excitonic correlations. Our experimental data provide insight on the intricate coupling between structural and electronic order in stabilizing the periodic-lattice-distortion/charge-density-wave state in 1 T − TiSe 2 . The results further show that electron-phonon coupling can lead to different, energy dependent phase-transition pathways in condensed matter systems, opening different possibilities in the conception of nonequilibrium phenomena at the ultrafast scale.

Journal Keywords: Charge density waves; Dynamical phase transitions; Excitons; Lattice dynamics; Transition-metal dichalcogenide; Resonant elastic x-ray scattering; X-ray diffraction

Subject Areas: Materials, Physics

Instruments: I16-Materials and Magnetism

Other Facilities: P09 beamline at PETRA III; X04SA beamline at Swiss Light Source


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