Ahmet Oral

Design of a self-aligned, wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with 10 nm magnetic force microscope resolution

We describe the design of a wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with a self-aligned fibre-cantilever mechanism. An alignment chip with alignment groves and a special mechanical design are used to eliminate tedious and time consuming fibre-cantilever alignment procedure for the entire temperature range. A low noise, Michelson fibre interferometer was integrated into the system for measuring deflection of the cantilever. The spectral noise density of the system was measured to be ∼12 fm/√Hz at 4.2 K at 3 mW incident optical power. Abrikosov vortices in BSCCO(2212) single crystal sample and a high density hard disk sample were imaged at 10 nm resolution to demonstrate the performance of the system.

Non-destructive patterning of 10 nm magnetic island array by phase transformation with low-energy proton irradiation

Nano-patterning on the order of sub-10 nm is integral to achieve high-density nano-scale devices for various data storage and data processing applications. However, the additional requirement of planarization and unwanted side-effects of physical or chemical etching have so far limited the patterning of sub-10 nm devices. In this work, we have demonstrated the creation of an array of ∼10 nm ferromagnetic islands through selective phase transformation of paramagnetic multilayers by low-energy proton irradiation. Paramagnetic Co3O4/Pd multilayers masked with patterned PMMA (polymethyl methacrylate) were reduced to ferromagnetic Co/Pd by proton irradiation. A clear contrast of the nano-islands was observed using magnetic force microscopy, establishing the formation of ferromagnetic nano-islands with perpendicular magnetic anisotropy. This process provides a way to circumvent the side-effects associated with both conventional nano-scale pattering and high-energy ion irradiation. Therefore, phase transformatio...

Structural and electrical characterization of electro spray deposited PZT sol-PZT nanopowder composite thick films

In piezoelectric market, infrared detectors, pyroelectric and piezoelectric sensors, microwave devices, actuators, transducers, non-volatile random access memories, and micro electromechanical systems are fabricated using lead zirconate titanate (PZT) based films. These films are deposited by chemical vapor deposition, physical vapor deposition spin coating, screen printing and electrospray deposition (ESD) technique. Among them, ESD is the most preferred method because of its high material efficiency, simplicity of experimental set up, wide choice of precursor and low cost. Therefore, the purpose of this study is to fabricate and characterize the ESD deposited PZT films. In our study, Pb(Zr0.52 Ti0.48)O3(PZT) nano powders (Nanotech Corp. Turkey) and MMC PZT sol (Mitsubishi Corp. Japan) combinations were mixed in various concentrations. Prepared composite PZT slurries were coated with ESD technique. Fabricated PZT thick films were characterized with scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction method (XRD) to evaluate surface and crystal structure of the films. The results show that, MMC sol and PZT nanopowder combinations provide smooth and homogeneous film surface, dense and non-cracked film microstructure was observed using excess PbO during sintering.