To understand the multistage phase transitions in V-based kagome metals inside the charge-density-wave (CDW) phase, we focus on the impact of the “mixed-type” Fermi surface because it is intact in the CDW state on the “pure-type” Fermi surface. On the mixed-type Fermi surface, moderate spin correlations develop, and we reveal that uniform (q=0) bond order is caused by the paramagnon interference mechanism, which is described by the Aslamazov-Larkin vertex correction. A dominant solution is Eg-symmetry nematic order, in which the director can be rotated arbitrarily. In addition, we obtain A_1g-symmetry order, which leads to the change in the lattice constants without symmetry breaking. The predicted Eg and A_1g channel fluctuations at q=0 can be observed by the elastoresistance measurements. These results are useful to understand the multistage phase transitions inside the 2×2 CDW phase. The present theory has a general significance because mixed-type Fermi surfaces (with multiorbital van Hove singularities) exist in various kagome lattice systems.

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