Schuricht Dirk, Essler Fabian H L, Jaefari Akbar, Fradkin Eduardo
The Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, OX1 3NP Oxford, United Kingdom.
Phys Rev Lett. 2008 Aug 22;101(8):086403. doi: 10.1103/PhysRevLett.101.086403. Epub 2008 Aug 20.
We determine the local density of states of one-dimensional incommensurate charge-density wave states in the presence of a strong impurity potential, which is modeled by a boundary. We find that the charge-density wave gets pinned at the impurity, which results in a singularity in the Fourier transform of the local density of states at momentum 2k_{F}. At energies above the spin gap we observe dispersing features associated with the spin and charge degrees of freedom, respectively. In the presence of an impurity magnetic field we observe the formation of a bound state localized at the impurity. All of our results carry over to the case of 1D Mott insulators by exchanging the roles of spin and charge degrees of freedom. We discuss the implications of our result for scanning tunneling microscopy experiments on spin-gap systems such as two-leg ladder cuprates.
我们确定了存在强杂质势（由边界建模）时一维非公度电荷密度波态的局域态密度。我们发现电荷密度波在杂质处被钉扎，这导致局域态密度在动量(2k_{F})处的傅里叶变换出现奇点。在高于自旋能隙的能量下，我们分别观察到与自旋和电荷自由度相关的色散特征。在存在杂质磁场的情况下，我们观察到在杂质处形成一个局域化的束缚态。通过交换自旋和电荷自由度的角色，我们所有的结果都适用于一维莫特绝缘体的情况。我们讨论了我们的结果对自旋能隙系统（如两腿梯形铜酸盐）扫描隧道显微镜实验的影响。
