Quantum criticality in Sc(V1-xCrx)6Sn6?

High-resolution thermal-expansion and heat-capacity measurements are combined to study the influence of chromium substitution on single crystals of the bi-layered Kagome metal ScV6Sn6. Similar to CsV3Sb5 [1], here we report that the charge-density wave (CDW) in ScV6Sn6 exhibits a colossal response to c-axis stress and no evidence for in-plane rotational symmetry breaking. The CDW is completely suppressed for   6%, where a significant enhancement of the Sommerfeld coefficient is found. A sign change of the Grüneisen parameter, a smoking gun of quantum phase transitions [2], is observed near this concentration. ... mehrFurther, the disappearance of the CDW is accompanied by the softening of an acoustic phonon mode and the emergence of a low-lying energy optical mode. A comparison of our results with hydrostatic-pressure measurements is made.
[1] M. Frachet et al., Phys. Rev. Lett. 132, 186001 (2024).
[2] M. Garst and A. Rosch, Phys. Rev. B 72, 205129 (2005).

High-resolution thermal-expansion and heat-capacity measurements are combined to study the influence
of chromium substitution on single crystals of the bi-layered Kagome metal ScV6Sn6. Similar to CsV3Sb5 [1],
here we report that the charge-density wave (CDW) in ScV6Sn6 exhibits a colossal response to c-axis stress
and no evidence for in-plane rotational symmetry breaking. The CDW is completely suppressed for   6
%, where a significant enhancement of the Sommerfeld coefficient is found. A sign change of the Grüneisen
parameter, a smoking gun of quantum phase transitions [2], is observed near this concentration. ... mehrFurther,
the disappearance of the CDW is accompanied by the softening of an acoustic phonon mode and the
emergence of a low-lying energy optical mode. A comparison of our results with hydrostatic-pressure
measurements is made.
[1] M. Frachet et al., Phys. Rev. Lett. 132, 186001 (2024).
[2] M. Garst and A. Rosch, Phys. Rev. B 72, 205129 (2005).