Controlling the Magneto-Optical Response in Ultrathin Films of EuO via Interface Engineering with Ferroelectric BaTiO.

Utilizing pulsed laser deposition, a film of EuO was deposited onto a Si(001) substrate with MgO buffer and compared to the same heterostructure with an additional BaTiO thin film on top of the EuO surface. X-ray diffraction (XRD) indicates the films crystallize into a preferred EuO(111) orientation; it also reveals the clear presence of EuSi which suggests Si or Eu diffuses across the MgO buffer layer. EuO films exhibit a ferromagnetic (FM) signature and temperature-dependent exchange bias, indicated by MOKE measurements, suggesting the presence of a magnetic order well above the EuO Curie temperature with possible origins in charge carrier density near the interface.

Chiral photocurrent in a Quasi-1D TiS(001) phototransistor.

The presence of in-plane chiral effects, hence spin-orbit coupling, is evident in the changes in the photocurrent produced in a TiS(001) field-effect phototransistor with left versus right circularly polarized light. The direction of the photocurrent is protected by the presence of strong spin-orbit coupling and the anisotropy of the band structure as indicated in NanoARPES measurements. Dark electronic transport measurements indicate that TiSis n-type and has an electron mobility in the range of 1-6 cmVs.

Surface Versus Bulk State Transitions in Inkjet-Printed All-Inorganic Perovskite Quantum Dot Films.

The anion exchange of the halides, Br and I, is demonstrated through the direct mixing of two pure perovskite quantum dot solutions, CsPbBr and CsPbI, and is shown to be both facile and result in a completely alloyed single phase mixed halide perovskite. Anion exchange is also observed in an interlayer printing method utilizing the pure, unalloyed perovskite solutions and a commercial inkjet printer. The halide exchange was confirmed by optical absorption spectroscopy, photoluminescent spectroscopy, X-ray diffraction, and X-ray photoemission spectroscopy characterization and indicates that alloying is thermodynamically favorable, while the formation of a clustered alloy is not favored.

Effect of Band Symmetry on Photocurrent Production in Quasi-One-Dimensional Transition-Metal Trichalcogenides.

Photocurrent production in quasi-one-dimensional (1D) transition-metal trichalcogenides, TiS(001) and ZrS(001), was examined using polarization-dependent scanning photocurrent microscopy. The photocurrent intensity was the strongest when the excitation source was polarized along the 1D chains with dichroic ratios of 4:1 and 1.2:1 for ZrS and TiS, respectively.

Tunable spin-state bistability in a spin crossover molecular complex.

The spin crossover (SCO) transitions at both the surface and over the entire volume of the [Fe{HB(pz)}(bipy)] polycrystalline films on AlO substrates have been studied, where pz  =  pyrazol-1-yl and bipy  =  2,2'-bipyridine. For [Fe{HB(pz)}(bipy)] films of hundreds of nm thick, magnetometry and x-ray absorption spectroscopy measurements show thermal hysteresis in the SCO transition with temperature, although the transition in bulk [Fe{HB(pz)}(bipy)] occurs in a non-hysteretic fashion at 157 K. While the size of the crystallites in those films are similar, the hysteresis becomes more prominent in thinner films, indicating a significant effect of the [Fe{HB(pz)}(bipy)]/AlO interface.

Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications.

A method for synthesizing photoactive inorganic perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are demonstrated. The ink synthesis is based on a simple wet chemical reaction and the inkjet printing protocol is a facile step by step method. The inkjet printed thin films have been characterized by X-ray diffraction, optical absorption spectroscopy, photoluminescent spectroscopy, and electronic transport measurements.

Composition-Dependent Charge Transport in Boron Carbides Alloyed with Aromatics: Plasma Enhanced Chemical Vapor Deposition Aniline/Orthocarborane Films.

Boron carbide films, alloyed with aniline moieties, were deposited by plasma enhanced chemical vapor deposition (PECVD) from aniline and orthocarborane precursors and were found to exhibit composition-dependent drift carrier lifetimes as derived from I( V) and C( V)) measurements. For a film with an aniline/carborane ratio of 5:1, the effective drift carrier lifetimes are ∼80 μs at low bias voltage but quickly drop to a few microseconds with increasing bias. A film with a 10:1 aniline/carborane ratio, however, exhibited lifetimes of ∼6 μs, or less, at 1 kHz, and much smaller values at 10 kHz.

Coexistence of Two Electronic Nano-Phases on a CHNHPbICl Surface Observed in STM Measurements.

Scanning tunneling microscopy is utilized to investigate the local density of states of a CHNHPbICl perovskite in cross-sectional geometry. Two electronic phases, 10-20 nm in size, with different electronic properties inside the CHNHPbICl perovskite layer are observed by the dI/dV mapping and point spectra. A power law dependence of the dI/dV point spectra is revealed.

Built-in Electric Field Induced Mechanical Property Change at the Lanthanum Nickelate/Nb-doped Strontium Titanate Interfaces.

The interactions between electric field and the mechanical properties of materials are important for the applications of microelectromechanical and nanoelectromechanical systems, but relatively unexplored for nanoscale materials. Here, we observe an apparent correlation between the change of the fractured topography of Nb-doped SrTiO3 (Nb:STO) within the presence of a built-in electric field resulting from the Schottky contact at the interface of a metallic LaNiO3 thin film utilizing cross-sectional scanning tunneling microscopy and spectroscopy. The change of the inter-atomic bond length mechanism is argued to be the most plausible origin.