Local impurity phase pinning and pinning force in charge density waves
Department of Physics, University of Ulm,
89069 Ulm, Germany
Published online: 15 May 1999
Starting from the static Fukuyama-Lee-Rice equation for a three-dimensional incommensurate charge density wave (CDW) in quasi one-dimensional conductors a solvable model for local phase pinning by impurities is defined and studied. We find that average CDW energy and average pinning force show critical behaviour with respect to the pinning parameter h. Specifically the pinning force exhibits a threshold at h=1 with exponent . Our model exemplifies a general concept of local impurity pinning in which the force exerted by the impurity on the periodic CDW structure becomes multivalued and metastable states appear beyond a threshold. It is found that local impurity pinning becomes less effective at low temperatures and may eventually cease completely. These results are independent of spatial dimensionality as expected for local impurity pinning. Comparison with Larkin's model is also made.
PACS: 71.45.Lr – Charge-density-wave systems / 71.55.Jv – Disordered structures; amorphous and glassy solids / 72.15.Nj – Collective modes (e.g., in one-dimensional conductors)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999