Abstract

BaNi2As2 is a non-magnetic analogue of BaFe2As2, the parent compound of a prototype pnictide high-temperature superconductor, displaying superconductivity already at ambient pressure. Recent diffraction studies demonstrated the existence of two types of periodic lattice distortions above and below the triclinic phase transition, suggesting the existence of an unconventional charge-density-wave (CDW) order. The suppression of CDW order upon doping results in a sixfold increase in the superconducting transition temperature and enhanced nematic fluctuations, suggesting CDW is competing with superconductivity. Here, we apply time-resolved optical spectroscopy to investigate collective dynamics in BaNi2As2. We demonstrate the existence of several CDW amplitude modes. Their smooth evolution through the structural phase transition implies the commensurate CDW order in the triclinic phase evolves from the high-temperature unidirectional incommensurate CDW, and may indeed trigger the structural phase transition. Excitation density dependence reveals exceptional resilience of CDW against perturbation, implying an unconventional origin of the underlying electronic instability.

Exotic states of solid-state matter give rise to collective excitations that can be probed by ultrafast spectroscopy. Here, a series of charge-density-wave amplitude modes are observed in a non-magnetic pnictide whose robustness against perturbations indicate an unconventional formation mechanism.

Details

Title
Dynamics of collective modes in an unconventional charge density wave system BaNi2As2
Author
Pokharel, Amrit Raj 1   VIAFID ORCID Logo  ; Grigorev, Vladimir 1 ; Mejas, Arjan 2 ; Dong, Tao 1 ; Haghighirad, Amir A. 3   VIAFID ORCID Logo  ; Heid, Rolf 3   VIAFID ORCID Logo  ; Yao, Yi 3 ; Merz, Michael 3   VIAFID ORCID Logo  ; Le Tacon, Matthieu 3   VIAFID ORCID Logo  ; Demsar, Jure 1   VIAFID ORCID Logo 

 Johannes Gutenberg University, Institute of Physics, Mainz, Germany (GRID:grid.5802.f) (ISNI:0000 0001 1941 7111) 
 Institute of Solid State Physics, TU Wien, Vienna, Austria (GRID:grid.5329.d) (ISNI:0000 0001 2348 4034) 
 Karlsruhe Institute of Technology, Institute for Quantum Materials and Technologies, Karlsruhe, Germany (GRID:grid.7892.4) (ISNI:0000 0001 0075 5874) 
Publication year
2022
Publication date
2022
Publisher
Nature Publishing Group
e-ISSN
23993650
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2673723943
Copyright
© The Author(s) 2022. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.