Quasiparticle scattering and local density of states in graphite.pdf

a r X i v : c o n d - m a t / 0 4 0 8 3 2 6 v 1 [ c o n d - m a t .m e s - h a l l ] 1 3 A u g 2 0 0 4 Quasiparticle scattering and local density of states in graphite Cristina Bena1 and Steven A. Kivelson2 1Department of Physics, University of California, Santa Barbara, CA 93106, USA 2Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547, USA (Dated: February 2, 2008) We determine the effect of quasiparticle interference on the spatial variations of the local density of states (LDOS) in graphite in the neighborhood of an isolated impurity. A number of characteristic behaviors of interference are identified in the Fourier transformed spectrum. A comparison between our results and scanning tunneling microscopy (STM) experiments could provide a critical test of the range (of energy) of applicability of the Fermi liquid description of graphite, where some evidence of the breakdown of Fermi liquid theory has recently been discussed. Moreover, given the similarity between the band structures of graphite and that of nodal quasiparticles in a d-wave superconductor, a comparison between results in the two materials is useful for understanding the physics of the cuprates. PACS numbers: 68.37.Ef, 81.05.Uw, 71.10.Ca There has been considerable interest recently in Fourier transform scanning tunneling spectroscopy (FT- STS) measurements, which may reveal some rather in- teresting electronic properties of conducting materials. In particular, recent experiments performed on certain cuprate high Tc superconductors 1,2,3,4,5,6,7, promise to shine some light on the low energy electronic excitations of the superconducting state, and on the pseudogap. In this paper we study a simple two dimensional sys- tem, graphite, which is generally believed to be a Fermi liquid. (Note, however, that this belief has been ques- tioned in Refs. 8.) Graphite has many similarities to the cuprates; its band structure consists of two bands that touch o