Suppression of the charge-density-wave state inSr10Ca4Cu24o41by external pressure

Abstract

The influence of external pressure on the charge-density-wave (CDW) ground state of the quasi-one-dimensional two-leg ladder compound ${\mathrm{Sr}}_{10}$${\mathrm{Ca}}_{4}$${\mathrm{Cu}}_{24}$${o}_{41}$ has been studied by optical reflectivity measurements as a function of temperature (10--300 K) and pressure $P$ (0.3--4.3 GPa) over the spectral range 580--6000 cm${}^{1}$. With increasing pressure the CDW transition temperature ${T}_{\text{CDW}}$ decreases with the linear pressure coefficient $\ensuremath{\approx}\ensuremath{-}$70 K/GPa, and above $\ensuremath{\approx}$3 GPa the CDW phase is suppressed at all temperatures. This behavior is similar to that in compounds ${\mathrm{Sr}}_{14\ensuremath{-}x}$${\mathrm{Ca}}_{x}$${\mathrm{Cu}}_{24}$${o}_{41}$ with increasing Ca content $x$ at ambient pressure, with the simple scaling $x\ensuremath{\approx}3\ifmmode\times\else\texttimes\fi{}P(\text{GPa})$. The size of the CDW gap decreases with increasing pressure, whereas the dimensionality of the high-temperature insulating phase in ${\mathrm{Sr}}_{10}$${\mathrm{Ca}}_{4}$${\mathrm{Cu}}_{24}$${o}_{41}$ within the ladder plane is hardly affected by external pressure.