• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.188.1-188.1
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• 2015

For present investigation Fe/MgO/Fe/Co multilayer stack is grown on Si substrate using e-beam evaporation in ultrahigh vacuum. This stack is irradiated perpendicularly by 120 MeV $Ag^{8+}$ at different fluences ranging from $1{\times}10^{11}$ to $1{\times}10^{13}ions/cm^2$ in high vacuum using 15UD Pelletron Accelerator at Inter University Accelerator Centre, New Delhi. Magnetic measurements carried out on pre and post irradiated stacks show significant changes in the shape of perpendicular hysteresis which is relevant with previous observation of re-orientation of magnetic moment along the direction of ion trajectory. However increase in plane squareness may be due to the modification of interface structure of stacks. X-ray reflectivity measurements show onset of interface roughness and interface mixing. X-ray diffraction measurements carried out using synchrotron radiation shows amorphous nature of MgO and Co layer in the stack. Peak corresponding body centered Fe [JCPDS-06-0696] is observed in X-ray diffraction pattern of pre and post irradiated stacks. Peak broadening shows granular nature of Fe layer. Estimated crystallite size is $22{\pm}1nm$ for pre-irradiated stack. Crystallite size first increases with irradiation then decreases. Structural quality of these stacks was further studied using transmission electron microscopic measurements. Thickness from these measurements are 54, 36, 23, 58 and 3 nm respectively for MgO, Fe, MgO, Fe+Co and Au layers in the stack. These measurements envisage poor crystallinity of different layers. Interfaces are not clear which indicate mixing at interface. With increase fluence mixing and diffusion was increased in the stack. X-ray absorption spectroscopic measurements carried out on these stacks show changes of Fe valence state after irradiation along with change of O(2p)-metal (3d) hybridized state. Valence state change predicts oxide formation at interface which causes enhanced in-plane magnetization.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.942-947
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• 2001

Thickness dependence of orientation on piezoelectric and electrical properties was investigated by PZT (52/48) films by diol based sol-gel method. The thickness of each layer by spinning at one time was $0.2{\mu}m$ and crack-free films could be successfully deposited on 4 inches Pt/Ti/$SiO_2$/Si substrates by 0.5 mol solutions in the range from $0.2{\mu}m$ to $3.8{\mu}m$. Excellent P-E hysteresis curves were achieved, which were attributed to the well-densified PZT films and columnar grain without pores or any defects between interlayers. The (111) preferred orientation of films were shown in the range of thickness below $1{\mu}m$. As the thickness increased, the (111) preferred orientation disappeared from $1{\mu}m$ to $3{\mu}m$ region, and the orientation of films became random above $3{\mu}m$. Dielectric constants and longitudinal piezoelectric coefficient, $d_{33}$, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of $1{\mu}m$.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.109-114
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• 2008

The samples were synthesized by using a solid state reaction. The X-ray diffraction pattern for $Ti_{0.96}Co_{0.02}Fe_{0.02}O_2$ showed a pure rutile phase with tetragonal structure, Mixtures of the proper proportions of the elements sealed in evacuated quartz ampoule were heated at $870{\sim}930^{\circ}C$ for one day and then slowly cooled down to room temperature at a rate of $10^{\circ}C$/h. In order to obtain single phase material, it was necessary to grind the sample after the first firing and to press the powders into pellets before annealing them for a second time in evacuated and sealed quartz ampoule. Magnetic properties have been investigated using the vibrating sample magnetometer (VSM). Room temperature magnetic hysteresis (M-H) curve showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied of 0.8 T was estimated to be about $1.5\;{\mu}_B$/CoFe. But the magnetic moment per Fe atom under the applied of 0.8 T was estimated to be about $0.02\;{\mu}_B$/CoFe without Ti-getter. Size of particles is about $1\;{\mu}m$ using the transmission electron microscope (TEM). The ingredients of sample are distributed irregular in particles. Only Fe get shown on the surface of particles.