Macroscopic Quantum Coherence of the Spin Triplet in the Spin-Ladder Compound Sr14Cu24O41

摘要

We report the direct observation by inelastic neutron scattering experimentsof a spin triplet of magnetic excitations in the response associated with theladders in the composite cuprate Sr14Cu24O41. This appears as a peak atq_{Q1D}=\pi and energy \Delta_1=32.5 meV, and we conjecture that all thetriplets making up this conspicuous peak have the same phase and thereforeinterpret it as the signature of the occurrence of quantum coherence along theladder direction between entangled spin pairs. From the comparison withprevious neutron and x-ray data, we conclude that the temperature evolution ofthis mode is driven by the crystallization of holes into a charge density wavein the ladder sublattice