SEMINAR on Disorder and strong electron correlations " Local density of states of 1D Mott insulators and CDW states with a boundary "

[Statistical Physics Group]

CONDENSED MATTER AND STATISTICAL PHYSICS SECTION




SEMINAR on

Disorder and strong electron correlations



Thursday, 16 April      -  11:00 a.m.



Seminar Room,  Leonardo Building - first floor



D. SCHURICHT

( RWTH Aachen )





" Local density of states of 1D Mott insulators

             and CDW states with a boundary "



Abstract



We determine the local density of states (LDOS) of one-dimensional  
incommensurate charge density wave (CDW) states in the presence of a  
strong impurity potential, which is modeled by a boundary. We find  
that the CDW gets pinned at the impurity, which results in a  
singularity in the Fourier transform of the LDOS 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.