Terahertz spectroscopic signature of the charge density wave in the spin-ladder compound, Sr14Cu24O41

Abstract

We provide spectroscopic evidence for the charge density wave (CDW) phason mode at ≈0.93 THz in the two-leg, spin-1/2 ladders of Sr14Cu24O41 using terahertz time-domain spectroscopy. We find that annealing in an oxygen atmosphere or doping with a low concentration of Co (precsim1%) does not affect the CDW phason mode. However, Co doping at higher concentrations (10%), wherein the Co enters the ladder layers, destabilizes the CDW. We believe that the suppression of the CDW phase is due to an increase in intraladder overlap integrals through the shrinkage of interplane distance upon Co doping.