Abstract
We present electrical resistivity and ac-susceptibility measurements of , and performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of . For and , a second CDW below increases with pressure until it reaches the () line. For , the lower CDW emerges as pressure is increased above . As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements of superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.
- Received 31 March 2015
- Revised 25 April 2015
DOI:https://doi.org/10.1103/PhysRevB.91.205114
©2015 American Physical Society