铜钛硒化物（CuxTiSe2）电荷密度波 - 超导体转变附近的量子和经典模式软化

Quantum and classical mode softening near the charge-density-wave-superconductor transition of CuxTiSe2.

作者信息

Barath H, Kim M, Karpus J F, Cooper S L, Abbamonte P, Fradkin E, Morosan E, Cava R J

机构信息

Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA.

出版信息

Phys Rev Lett. 2008 Mar 14;100(10):106402. doi: 10.1103/PhysRevLett.100.106402. Epub 2008 Mar 12.

DOI:10.1103/PhysRevLett.100.106402

PMID:18352215

Abstract

Temperature- and x-dependent Raman scattering studies of the charge-density-wave (CDW) amplitude modes in Cu(x)TiSe(2) show that the amplitude mode frequency omega(0) exhibits identical power-law scaling with the reduced temperature T/T(CDW) and the reduced Cu content x/x(c), i.e., omega(0) approximately (1-p)(0.15) for p=T/T(CDW) or x/x(c), suggesting that mode softening is independent of the control parameter used to approach the CDW transition. We provide evidence that x-dependent mode softening in Cu(x)TiSe(2) is associated with the reduction of the electron-phonon coupling constant, and that x-dependent "quantum" (T approximately 0) mode softening suggests the presence of a quantum critical point within the superconductor phase of Cu(x)TiSe(2).

摘要

对Cu(x)TiSe(2)中电荷密度波（CDW）振幅模式的温度和x依赖拉曼散射研究表明，振幅模式频率ω(0)与约化温度T/T(CDW)和约化铜含量x/x(c)呈现相同的幂律标度，即对于p = T/T(CDW)或x/x(c)，ω(0)约为(1 - p)(0.15)，这表明模式软化与用于接近CDW转变的控制参数无关。我们提供的证据表明，Cu(x)TiSe(2)中x依赖的模式软化与电子-声子耦合常数的降低有关，并且x依赖的“量子”（T约为0）模式软化表明在Cu(x)TiSe(2)的超导相内存在量子临界点。