The family of kagome metals AV3Sb5 (A: K, Rb, Cs) presents an intriguing interplay of non-trivial electronic band topology, superconductivity, electronic correlations leading to charge density wave (CDW) instability, and magnetic frustration due to its unique crystalline structure.
In collaboration with a team from the Chinese University of Hong Kong and the high magnetic field laboratory LNCMI of the CNRS in Grenoble, researchers from PHELIQS conducted a detailed study of the Fermi surface of CsV3Sb5, a member of the kagome family. In this material, the Fermi surface is reconstructed due to the CDW instability.
To better understand the material, it is crucial to know the Fermi surface of the “pristine” metal, before the electronic instability sets in. This has been achieved in the present study through a probe of the Fermi surface of CsV3Sb5 as a function of hydrostatic pressures up to 30 kbars and high magnetic fields up to 30 T. The first outcome is the discovery of a large Fermi surface, which is a signature of the pristine state and absent in the reconstructed Fermi surface at ambient pressure.
It is the first time that such a strong effect of the CDW instability on the Fermi surface is directly demonstrated by quantum oscillations. Another important result is that the effective mass of the charge carriers is noticeably enhanced near the critical pressure where the CDW instability is suppressed by pressure. Both findings emphasize the influence of the charge density wave on the electronic structure, together with the sensitivity of the electronic correlations driving this electronic instability to a modest pressure.
Figure 01: calculated Fermi surface of the pristine CsV3Sb5 at 30 kbar for Band 67. (Credit CEA)
Figure 02: The Vanadium atoms form a perfect Kagome lattice (named after a traditional Japanese bamboo basket) in the crystal structure of AV3Sb5 at room temperature. Lowering the temperature, this perfect lattice is broken by a charge density wave instability. (Credit CEA)
Collaboration
- Chinese University of Hong Kong
- The high magnetic field laboratory LNCMI of the CNRS in Grenoble
Contact: Georg Knebel and Alexandre Pourret