Luttinger liquid behaviour of Li0.9Mo6O17 studied by scanning tunnelling microscopy
Scanning tunnelling spectroscopy (STS) was used to study the Luttinger liquid behaviour of the purple bronze Li0.9Mo6O17 in the temperature range 5 K < T < 300 K. In the entire temperature range the suppression of the density of states at the Fermi energy can be fitted very well by a model describing the tunnelling into a Luttinger liquid at ambient temperature. The power-law exponent extracted from these fits reveals a significant increase above 200 K. It changes from α = 0.6 at low temperature to α = 1.0 at room temperature.
Quantum critical scaling in the single-particle spectrum of a novel anisotropic metal.
We report an angle resolved photoemission spectroscopy study of quantum critical scaling in the single-particle spectral function of a novel anisotropic metal Li_{0.9}Mo_{6}O_{17}. We find a temperature (T) scaling exponent value and also low-T angle resolved photoemission spectroscopy line shapes that are very challenging for current one-dimensional theory frameworks. These results add a new spectroscopic component to a growing collection of puzzling low-T transport behaviors of this material.
Diffuse x-ray and inelastic neutron scattering study of the spin Peierl's transition in N-methyl-N-ethyl-morpholinium bistetracyanoquinodimethane [MEM (TCNQ) 2 ]
X-ray and neutron scattering techniques have been used to investigate the spin Peierl's transition in $N$-methyl-$N$-ethyl-morpholinium bistetracyanoquinodimethane [MEM ${(\mathrm{TCNQ})}_{2}$]. Both techniques reveal a doubling of the $c$-axis stacking of the TCNQ molecules below the transition. Diffuse x-ray scattering was observed well above the transition at the position of the low-temperature superlattice reflections. The geometry of the scattering showed that the critical scattering related to the structural changes at ${T}_{c}$ results from fluctuations of a mainly transverse nature. Neutron scattering measurements revealed no softening of longitudinal-acoustic phonons at the transition. It was impossible to determine the position of the transverse-acoustic phonons, because they have either very low energies or very large linewidths; therefore, we cannot define the fluctuations to be of a static or dynamic character.