The conducting interface of LaAlO3/SrTiO3 heterostructures has been studied by hard X-ray photoelectron spectroscopy. From the Ti 2p signal and its angle-dependence we derive that the thickness of the electron gas is much smaller than the probing depth of 4 nm and that the carrier densities vary with increasing number of LaAlO3 overlayers. Our results point to an electronic reconstruction in the LaAlO3 overlayer as the driving mechanism for the conducting interface and corroborate the recent interpretation of the superconducting ground state as being of the BerezinskiiKosterlitz-Thouless type.

We investigated the electronic properties of the molecular magnetic nanotoruses [FeIII 10LnIII 10(Me‐tea)10(Me‐teaH)10(NO3)10], examining the dependence on the lanthanide (Ln) of both the intra and intermolecular electronic channels. Using femtosecond absorption spectroscopy we show that the intramolecular electronic channels follow a three‐step process, which involves vibrational cooling and crossing to shallow states, followed by recombination. A comparison with the energy gaps showed a relationship between trap efficiency and gaps, indicating that lanthanide ions create trap states to form excitons after photo‐excitation. Using high‐resistance transport measurements and scaling techniques, we investigated the intermolecular transport, demonstrating the dominant role of surface‐limited transport channels and the presence of different types of charge traps. The intermolecular transport properties can be rationalized in terms of a hopping model, and a connection is provided to the far‐IR spectroscopic properties. Comparison between intra and intermolecular processes highlights the role of the excited electronic states and the recombination processes, showing the influence of Kramers parity on the overall mobility.

We report transport measurements on a quantum dot in a partly suspended carbon nanotube. Electrostatic tuning allows us to modify and even switch "on" and "off" the coupling to the quantized stretching vibration across several charge states. The magnetic-field dependence indicates that only the two-electron spin-triplet excited state couples to the mechanical motion, indicating mechanical coupling to both the valley degree of freedom and the exchange interaction, in contrast to standard models.

We demonstrate single-electron addition to different strands of a carbon nanotube rope. Anticrossings of anomalous conductance peaks occur in quantum transport measurements through the parallel quantum dots forming on the individual strands. We determine the magnitude and the sign of the hybridization as well as the Coulomb interaction between the carbon nanotube quantum dots, finding that the bonding states dominate the transport. In a magnetic field the hybridization is shown to be selectively suppressed due to spin effects. Molecular electronics and spintronics aim at exploiting the chemical versatility of molecules to control charge and magnetism in nanoscale devices. However, the assembly of molecular structures in junctions for electric and magnetic manipulation is a challenging task.1-4 Carbon nanotubes (CNTs) are particularly promising as building blocks of new devices for nanoelectronics, 5-8 which exhibit interesting spin properties 9-12 and can be useful for quantum information processing.13,14 Fundamental aspects of single-molecule devices require an understanding of strong perturbations by environmental effects, for example, the interaction with contacts or neighboring molecules. 15 These interactions can, in principle, be studied on a single-molecule level using scanning probe techniques as for instance scanning near-field optical microscopy, 16 tip-enhanced Raman spectroscopy 17,18 or scanning tunneling spectroscopy (STS). 19 However, in situ characterization of actual devices, for example, field-effect transistors, is difficult to implement and only STS can detect spin-dependent phenomena.As an alternative approach, one may exploit the differential electrostatic gating effect, which was found to occur for contacted CNTs filled with fullerenes 20 and for single molecules in nanojunctions. 15 In this respect, bundled CNTs are interesting: Within a rope one expects the strands to be at a different potential and to respond differently to the external electric fields due to electrostatic effects. 21 Low-temperature transport spectroscopy is sensitive to these potential variations on the sub-meV scale, allowing the study of interactions between coupled nanoscale conductors.In this Rapid Communication we show that transport spectroscopy can resolve both charge addition to individual strands of a single CNT rope as well as the coupling between these strands caused by molecular interactions. We determine the hybridization and the electrostatic interaction between parallel quantum dots (QDs) forming on the different strands. We extract both the magnitude and the sign of the hybridization and find that current transport occurs via the bonding states of the coupled QD system. Furthermore, by applying a magnetic field the electronic hybridization is selectively suppressed due to spin effects. This offers prospects for accessing individual charge and spin degrees of freedom in coupled carbon-based molecular systems.The CNTs of the reported device were grown on a Si/SiO 2 substrate by chemical vapor deposition ...