Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 92: Symposium One-dimentional Metals: Reality or Fiction (DS jointly with HL, O, TT)

O 92.2: Hauptvortrag

Freitag, 4. April 2014, 10:10–10:50, HSZ 02

1 + δ: Tuning the Dimensionality of Organic Conductors — •Martin Dressel — 1. Physikalisches Institut, Universität Stuttgart

Organic charge-transfer salts are prime candidates for tuning the dimension by applying pressure. Strictly one-dimensional systems, such as the Fabre salts (TMTTF)₂ X, are Mott insulators that undergo a deconfinement transition towards a Luttinger liquid and eventually a two-dimensional Fermi liquid if the interchain interaction increases with pressure. The deconfinement transition can be identified when the transverse hopping integral 2t_⊥=Δ_ρ, the Mott gap. Ab-initio density functional theory allows us to study the influence of temperature and pressure on the electronic band structure.

Quasi-one-dimensional organic conductors, like the Bechgaard salts (TMTSF)₂ X, exhibit a cross-over from a Luttinger liquid to a Fermi liquid behavior upon cooling and application of external pressure. Frequency and temperature dependent transport measurement yield a change in power-laws and Luttinger exponent.

Often the metallic phase is not stable in reduced dimensions: at low temperatures the electronic charges and spins tend to arrange themselves in an orderly fashion due to relatively strong correlations. There are a growing number of molecular materials where electronic degrees of freedom and electronic interactions are directly responsible for electric polarization and ferroelectric transition, termed electronic ferroelectricity. Recently, it was discovered that charge order not only produces ferroelectricity but also breaks the symmetry of the magnetic degree of freedom in organic quantum spin chains.