We have studied the effect of substrate-induced strain on the properties of the hole-doped manganite (La1−yPry)0.67Ca0.33MnO3 (y = 0.4, 0.5 and 0.6) in order to distinguish between the roles played by long-range strain interactions and quenched atomic disorder in forming the micrometerscale phase separated state. We show that a fluid phase separated (FPS) state is formed at intermediate temperatures similar to the strain-liquid state in bulk compounds, which can be converted to a metallic state by applying an external electric field. In contrast to bulk compounds, at low temperatures a strain stabilized ferromagnetic metallic (FMM) state is formed in the y = 0.4 and 0.5 samples. However, in the y = 0.6 sample a static phase separated (SPS) state is formed similar to the strain-glass phase in bulk compounds. Hence, we show that long-range strain interaction plays a dominant role in forming the micrometer-scale phase separated state in manganite thin films.PACS numbers: 75.47. Lx, 73.50.Fq, 75.47.Gk, Multiphase coexistence in hole-doped manganites is a result of the competition between phases of different electronic, magnetic and structural orders [1,2]. This competition leads to large changes in the physical properties of manganites due to small perturbations e.g. colossal negative magnetoresistance (CMR). At low temperatures the two competing phases are the ferromagnetic metallic (FMM) and charge-ordered insulating (COI) phases. In manganites with greater average A-site cation radii ( r A ) and consequently a larger effective one-electron bandwidth (W ) (e.g. La 1−x Ca x MnO 3 , 0.2 < x < 0.5), the pseudocubic FMM phase is favored at low temperatures [3]. When smaller ions such as Pr are substituted at the A-site, r A and W are reduced. In these compounds the double-exchange mechanism is suppressed and hence the pseudotetragonal (distorted) COI phase has a comparable free energy to the FMM phase, resulting in micrometer scale phase separation [4]. It was shown that in the presence of quenched disorder introduced by the ions of different radii, the similarity of the free energies leads to coexistence of the two competing phases [2]. However, the observation of martensitic strain accommodation in manganites [5] and fluid-like growth of the FMM phase observed in magnetic force microscopy (MFM) images of phase separated manganites [6], suggests that the phases are not pinned. In fact, due to this behavior the phase separated state in manganites has been described as an "electronic soft matter" state [2,7]. These observations can be explained by an alternative model which shows that the different crystal structures of the FMM and COI phases generate long range strain interactions leading to an intrinsic elastic energy landscape, which leads to micrometer scale phase separation even without quenched disorder [1]. To understand the underlying mechanism for micrometer scale phase separation in manganites, it is essential to distinguish between the roles played by quenched disorder and long range strain interactions. We ...

In this paper we demonstrate high-quality, uniform dry transfer of graphene grown by chemical vapor deposition on copper foil to polystyrene. The dry transfer exploits an azide linker molecule to establish a covalent bond to graphene and to generate greater graphene-polymer adhesion compared to that of the graphene-metal foil. Thus, this transfer approach provides a novel alternative route for graphene transfer, which allows for the metal foils to be reused.

The stability of the surface of vacuum-cleaved topological insulator Bi 2 Se 3 single crystals is investigated with high-resolution synchrotron-based photoelectron spectroscopy. While the surface is stable at room temperature in vacuum, a Bi 2 layer always forms at the surface of Bi 2 Se 3 upon even brief (5 min) exposure to atmosphere. This is accompanied by a depletion of selenium in the near surface region and a 1.4 eV decrease in work function. The Bi 2 surface is found to be stable upon return to ultrahigh vacuum conditions but is unstable with prolonged exposure to air, ultimately resulting in two possible different reconstructed surfaces, explaining previous contradictory results on long-term atmosphere exposure of Bi 2 Se 3 .

The C60-thin film pentacene interface was investigated using scanning tunneling microscopy, atomic force microscopy, and ultraviolet photoemission spectroscopy. C60 deposition on a multilayer pentacene film (standing) yields an interface dominated by C60 clusters, regardless of the underlying substrate. Three-dimensional cluster growth dominates due to weak interactions with the underlying Pn. C60 cluster size and density on sequential Pn layers suggest an Ehrlich–Schwoebel-type barrier at Pn layer boundaries. Cluster formation reduces the C60 lowest unoccupied molecular orbital–Pn highest occupied molecular orbital (HOMO) separation, while increasing the respective HOMO-HOMO offset. Heterostructure fabrication protocols can alter interface morphology and induce band shifts on the order of 0.3 eV.