Pressure-induced crossover between charge-density-wave phases of FeGe

We seek to investigate the high-pressure crystal structure of FeGe using low-temperature single-crystal XRD. Among several candidate kagome metals, FeGe is unique in that it combines magnetic order with a charge-density-wave (CDW) instability at ambient pressure. Recent resistivity measurements showed an unexpected stabilization of the CDW phase of FeGe upon compression, which is contrary to the conventional scenario of CDW suppressed by pressure. Interestingly, above 20 GPa another CDW phase of unknown origin was detected. We seek to determine the nature of this high-pressure CDW-II phase, the mechanism of its formation from the ambient-pressure CDW-I phase, and the reasons for the initial stabilization of CDW-I under pressure.