The growing charge-density-wave order in CuTe lightens and speeds up electrons.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39472563.
- Also identified by DOI 10.1038/s41467-024-53653-z and PMC identifier 11522371.
- Licence recorded as CC BY-NC-ND.
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Abstract
Charge density waves (CDWs) are pervasive orders in solids that usually enhance the effective mass (m*) and reduce the Fermi velocity ( <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>v</mi></mrow> <mrow><mi>F</mi></mrow> </msub> </math> ) of carriers. Here, we report on the inverse - a reduced m* and an enhanced <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>v</mi></mrow> <mrow><mi>F</mi></mrow> </msub> </math> correlated with the growth of the CDW order in CuTe with gapped, practically linearly dispersing bands - reminiscent of emergent CDW-gapped topological semimetals. Using momentum-dependent electron energy-loss spectroscopy (q-EELS), we simultaneously capture m* and <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>v</mi></mrow> <mrow><mi>F</mi></mrow> </msub> </math> of the CDW-related, practically linearly dispersing electrons by plasmon dispersions across the transition (335 K, T<sub>CDW</sub>), with m* of 0.28 m<sub>0</sub> (m<sub>0</sub>, the electron rest mass) and <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>v</mi></mrow> <mrow><mi>F</mi></mrow> </msub> </math> of ~ 0.005c (c, the speed of light) at 300 K. With the growth of the CDW order-parameter strength toward 100 K, the electrons become lighter and move faster by ~ 20%. Thorough inspection below T<sub>CDW</sub> unveils the essential role of the increasing opening of the CDW gap. CuTe is a rich platform for the exploration of CDW/correlation physics with q-EELS established as a useful probe for this type of physics.