The changes of molecular conformation, contact geometry, and metal-molecule bonding are revealed by inelastic-electron-tunneling spectroscopy measurements characterizing the molecular vibrational modes and the metal-phonon modes in alkanedithiol molecular junctions at low temperature. Combining inelastic-electron-tunneling spectroscopy with mechanical control and electrode material variation (Au or Pt) enables separating the influence of contact geometry and of molecular conformation. The mechanical strain of different electrode materials can be imposed onto the molecule, opening a new route for controlling the charge transport through individual molecules.

Keywords: Layered compounds / Thin films / Electronic structure / Thermoelectric materials / Charge transfer (SnSe) 1.2 TiSe 2 was found to self-assemble from a precursor containing modulated layers of Sn-Se and Ti-Se over a surprisingly large range of layer thicknesses and compositions. The constituent lattices form an alternating layer superstructure with rotational disorder present between the layers. This compound was found to have the highest Seebeck coefficient measured for analogous TiX 2 containing misfit layered compounds to date, suggesting potential for [a]83 low-temperature thermoelectric applications. Electrical characterization suggests that electrons transferred from SnSe to TiSe 2 are responsible for the higher carrier concentration observed relative to bulk TiSe 2 . The transfer of charge from one constituent to the other may provide a mechanism for doping layered dichalcogenides for various applications without negatively affecting carrier mobility.

We present a comprehensive study of the conductance behavior of atomic-size contacts made of ferromagneti c metals (Co) or noble metals (Au) with ferromagneti c electrodes (Co). In order to separate the influence of the large electrodes fro m the influence of the contacts themse lves, we used different sampl e geometri es. T hese include combinati ons of nonmagnetic electrodes connected to magneti c bridges and vice versa as well as di fferent orientati ons of the mag netic fi eld. The magnetores istance (MR) curves show very rich behavi or with strong MR rati os (MRR). In all geometries the MRR va lu es are of comparabl e size, reaching up to a few thousand percent in the tunneli ng regime. We study the poss ibl e influence of the mi cromag neti c order of the domain s in the vic inity of the contac t as well as balli sti c MR, giant MR, tun nel MR , atomically enh anced ani sotropi c MR (AAMR), and magnetostri cti on. We co nclude that AAMR is the most important origin for the MR at hi gh magnet ic fie lds (iBI > 2 T) , while magnetostri ct ion, tunnel MR , and giant MR govern the low-fie ld reg ime (IBI < 2 T).

Here we report for the first time on a complete simulation assisted "material to module" development of a high performance thermoelectric generator (TEG) based on the combination of a phase change material and established thermoelectrics yielding the compositions (1 - x)(GeTe) x(Bi(2)Se(0.2)Te(2.8)). For the generator design our approach for benchmarking thermoelectric materials is demonstrated which is not restricted to the determination of the intrinsically imprecise ZT value but includes the implementation of the material into a TEG. This approach is enabling a much more reliable benchmarking of thermoelectric materials for TEG application. Furthermore we analyzed the microstructure and performance close to in-operandi conditions for two different compositions in order to demonstrate the sensitivity of the material against processing and thermal cycling. For x = 0.038 the microstructure of the as-prepared material remains unchanged, consequently, excellent and stable thermoelectric performance as prerequisites for TEG production was obtained. For x = 0.063 we observed strain phenomena for the pristine state which are released by the formation of planar defects after thermal cycling. Consequently the thermoelectric performance degrades significantly. These findings highlight a complication for deriving the correlation of microstructure and properties of thermoelectric materials in general.