ABSTRACT. CoFe2O4 (CFO)-BiFeO3 (BFO) nanocomposites are an intriguing option for future memory and logic technologies due to the magnetoelctric properties of the system. However, these nanocomposites form with CFO pillars randomly located within a BFO matrix, making implementation in devices difficult. To overcome this, we present a technique to produce patterned nanocomposites through self-assembly. CFO islands are patterned on Nb-doped SrTiO3 to direct the self-assembly of epitaxial CFO-BFO nanocomposites, producing square arrays of CFO pillars.2 Multiferroic nanocomposite films have been heavily studied for their potential applications in magnetoelectric systems. 1 The CoFe2O4-BiFeO3 (CFO and BFO, respectively) system has generated particular interest due to the magnetoelastic properties of CFO 2 and the combination of ferroelectricity and anti-ferromagnetism in BFO 3 . It has been shown that when CFO and BFO are codeposited via physical vapor deposition at high temperatures on a SrTiO3 (001) substrate that the materials will spontaneously phase segregate to produce an epitaxial CFO pillar in an epitaxial BFO matrix, which is referred to as a 1-3 nanocomposite. 4 The CFO pillars form faceted structures with {110}-type interfaces with the BFO matrix and {111}-facets on the surface, protruding above the matrix. 5 The pattern of the CFO pillars in the structure is essentially random, since they are formed through the nucleation of a CFO island on the substrate, while BFO wets the remaining surface. Thus, to control the location of the pillars a means of controlling the nucleation site for the CFO island is needed. CFO-BFO composites have been found to demonstrate magnetoelectric coupling, allowing for electrical control of the magnetic anisotropy of the CFO pillars. 6 , 7 Based on these properties, the composite system has been proposed for both magnetoelectric memory 8 and logic 9 applications. In particular, the reconfigurable array of magnetic automata (RAMA) 9,10 is a nanomagnetic logic system based on the magnetic quantum cellular automata (MQCA) logic architecture 11 which would use a CFO-BFO 1-3 composite with the pillars arranged in a square array to create a reprogrammable logic system. However, in order to make devices using these composites, the ability to place the pillars into pre-determined arrays is required.Previous work in patterning multiferroic nanocomposites has been limited. One method to produce patterned magnetoelectric composites is to use a porous anodic aluminum oxide (AAO) film as a liftoff mask during deposition, which produces a hexagonal array pattern. 12,13 In one approach, a BaTiO3-CoFe2O4 (BTO-CFO) multilayer is deposited onto the AAO film on an STO substrate, which yields a small amount of magnetoelectric response. 12 Another technique is to use the AAO film to form CFO islands and then overcoat the islands with ferroelectric Pb(Zr,Ti)O3 (PZT), which yields a composite that is both ferroelectric and ferromagnetic. 13 Others have used a SiN membrane as a shadow mask to 3 ...

The low-temperature phase transitions of thermoelectric Zn 4 Sb 3 have been characterized using singlecrystal X-ray diffraction, electrical resistance, and thermal conductivity measurements. Room-temperature stable, disordered β-Zn 4 Sb 3 undergoes a phase transition at 254 K to ordered R-Zn 4 Sb 3 , which has an ideal composition Zn 13 Sb 10 . Below 235 K, a second low-temperature phase (R′-Zn 4 Sb 3 ) can be detected. The sequence of phase transitions β-R-R′ is reversible. The R-R′ transformation originates from a slight Zn deficiency with respect to Zn 13 Sb 10 . The actual composition of Zn 4 Sb 3 is Zn 13-δ Sb 10 .

We report a simple one-pot strategy to prepare surface-function-alized, water-dispersible iron oxide nanoparticles. Small organic molecules that have desired functional groups such as amines, carboxylics, and thiols are chosen as capping agents and are injected into the reaction medium at the end of the synthesis. A diversity of functionalities are effectively introduced onto the surface of the nanoparticles with a minimal consumption of solvents and chemical resources by simply switching the capping ligand to form the ligand shell. The resulting nanocrystals are quasi-spherical and narrowly size-distributed. Energy-dispersive X-ray analysis and Fourier transform infrared spectroscopy studies suggest a successful surface modification of iron oxide nanoparticles with selected functionalities. The colloidal stabilities are characterized by dynamic light scattering and zeta potential measurements. The results imply that functionalized nanoparticles are very stable and mostly present as individual units in buffer solutions. The pedant functional groups of the capping ligand molecules are very reactive, and their availabilities are investigated by covalently linking fluorescent dyes to the nanoparticles through the cross-linking of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The quenched quantum yield and shortened lifetime of the dyes strongly indicate a direct bonding between the functional group of the nanoparticles and the fluorescent molecules.