Creation of a novel inverted charge density wave state.

Yingchao Zhang,Mengxue Guan,Henry C Kapteyn,Margaret M Murnane,Yaobo Huang,Xun Shi,Kai Rossnagel,Sheng Meng,Yigui Zhong,Tika R Kafle,Hong Ding,Michael Bauer,Wenjing You

doi:10.1063/4.0000132

Abstract

Charge density wave (CDW) order is an emergent quantum phase that is characterized by periodic lattice distortion and charge density modulation, often present near superconducting transitions. Here, we uncover a novel inverted CDW state by using a femtosecond laser to coherently reverse the star-of-David lattice distortion in 1T-TaSe2. We track the signature of this novel CDW state using time- and angle-resolved photoemission spectroscopy and the time-dependent density functional theory to validate that it is associated with a unique lattice and charge arrangement never before realized. The dynamic electronic structure further reveals its novel properties that are characterized by an increased density of states near the Fermi level, high metallicity, and altered electron–phonon couplings. Our results demonstrate how ultrafast lasers can be used to create unique states in materials by manipulating charge-lattice orders and couplings.

Highlights

The correlated interactions of electrons and atoms in crystalline materials, including electron–phonon coupling,1,2 play a crucial role in stabilizing emergent quantum phases such as charge density wave (CDW) order and superconductivity
We track the signature of this novel Charge density wave (CDW) state using time- and angleresolved photoemission spectroscopy and the time-dependent density functional theory to validate that it is associated with a unique lattice and charge arrangement never before realized
We find that the Ta 5d bandwidth [i.e., the energy range of the full dispersive band, see Fig. 2(d)] along the C–M direction increases as the material transforms from the usual CDW state into the normal state, before decreasing again as the material enters an inverted CDW state

Summary

Introduction

The correlated interactions of electrons and atoms in crystalline materials, including electron–phonon coupling,1,2 play a crucial role in stabilizing emergent quantum phases such as charge density wave (CDW) order and superconductivity. We uncover a novel inverted CDW state by using a femtosecond laser to coherently reverse the star-of-David lattice distortion in 1T-TaSe2.

Results

Conclusion