  The strange metal (SM) state, characterized by a linear-in-temperature
resistivity, is often seen in the normal state of high temperature
superconductors. It is believed that the SM state is one of the keys to
understand the underlying mechanism of high-Tc superconductivity. Here we
report the first observation of the concurrent breakdown of the SM normal state
and superconductivity at a pressure-induced quantum critical point in an
iron-pnictide superconductor, Ca10(Pt4As8)((Fe0.97Pt0.03)2As2)5. We find that,
upon suppressing the superconducting state by applying pressure, the power
exponent changes from 1 to 2, and the corresponding coefficient A, the slope of
the temperature-linear resistivity per FeAs layer, gradually diminishes. At a
critical pressure (12.5 GPa), A and Tc go to zero concurrently,where a quantum
phase transition (QPT) from a superconducting state with a SM normal state to a
non-superconducting Fermi liquid state takes place. Scaling analysis on the
results obtained from the pressurized 1048 superconductor reveals that A and Tc
have a positive relation, which exhibits a similarity with that is seen in
other chemically-doped unconventional superconductors, regardless of the type
of the tuning method (doping or pressurizing), the crystal structure, the bulk
or film superconductors and the nature of dopant. These results suggest that
there is a simple but powerful organizational principle of connecting the SM
normal state with the high-Tc superconductivity.
