Charge Transport in the Presence of Correlations and Disorder: Organic Conductors and Manganites.

One of the most fascinating aspects of condensed matter is its ability to conduct electricity, which is particularly pronounced in conventional metals such as copper or silver. Such behavior stems from a strong tendency of valence electrons to delocalize in a periodic potential created by ions in the crystal lattice of a given material. In many advanced materials, however, this basic delocalization process of the valence electrons competes with various processes that tend to localize these very same valence electrons, thus driving the insulating behavior.

(Magneto)Transport Properties of (TiZrNbNi)Cu and (TiZrNbCu)Co Complex Amorphous Alloys.

We present a systematic study of electrical resistivity, superconductive transitions and the Hall effect for three systems of compositionally complex amorphous alloys of early (TE) and late (TL) transition metals: (TiZrNbNi)1-xCux and (TiZrNbCu)1-xCox in a broad composition range of 0 View Article and Find Full Text PDF

Electronic Structure of Quasi-Freestanding WS/MoS Heterostructures.

Growth of 2D materials under ultrahigh-vacuum (UHV) conditions allows for an in situ characterization of samples with direct spectroscopic insight. Heteroepitaxy of transition-metal dichalcogenides (TMDs) in UHV remains a challenge for integration of several different monolayers into new functional systems. In this work, we epitaxially grow lateral WS-MoS and vertical WS/MoS heterostructures on graphene.

Role of microscopic phase separation in gelation of aqueous gelatin solutions.

Using a unique home-made cell for four-contact impedance spectroscopy of conductive liquid samples, we establish the existence of two low frequency conductivity relaxations in aqueous solutions of gelatin, in both liquid and gel states. A comparison with diffusion measurements using pulsed field gradient NMR, and circular dichroism spectroscopy, shows that the faster relaxation process is due to gelatin macromolecule self-diffusion. This single molecule diffusion is mostly insensitive to the macroscopic state of the sample, implying that we have a clear separation of gelatin molecules into a free and network-bound phase.

Four-contact impedance spectroscopy of conductive liquid samples.

We present an improved approach to the impedance spectroscopy of conductive liquid samples using four-electrode measurements. Our method enables impedance measurements of conductive liquids down to the sub-Hertz frequencies, avoiding the electrode polarization effects that usually cripple standard impedance analysers. We have successfully tested our apparatus with aqueous solutions of potassium chloride and gelatin.

Unconventional charge-density wave in the organic conductor alpha-(BEDT-TTF)2KHg(SCN)4.

The low temperature phase (LTP) of alpha-(BEDT-TTF)2KHg(SCN)(4) salt is known for its surprising angular dependent magnetoresistance (ADMR), which has been studied intensively in the last decade. However, the nature of the LTP has not been understood until now. Here we analyze theoretically ADMR in unconventional (or nodal) charge-density wave (UCDW).