• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.42-43
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• 2002

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.34-35
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• 2001

• Journal of the Korean Magnetics Society
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• v.15 no.6
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• pp.311-314
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• 2005

We investigated the composition dependence of the tunneling magnetoresistance (TMR) behavior and the stability of the magnetic tunnel junctions (MTJs) with TiAlOx barrier and the microstructural evolution of TiAl alloy films. The TMR ratio increased up to $49\%$ at $5.33\;at\%$ Ti. In addition, a significant tunneling magnetoresistance (TMR) value of $20\%$ was maintained after annealing at $450^{\circ}C$, and the breakdown voltage ($V_B$) of and 1.35 V were obtained in the MTJ with $5.33\;at\%$ Ti-alloyed AlOx barrier. These results were closely related to the enhanced quality of the barrier material microstructure in the pre-oxidation state. Ti alloying enhanced the barrier/electrode interface uniformity and reduced microstructural defects. These structural improvements enhanced not only the TMR effect but also the thermal and electrical stability of the MTJs.

• Journal of the Korean Magnetics Society
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• v.18 no.4
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• pp.154-158
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• 2008

Magnetite($Fe_3O_4$) is currently one of key materials for applications in magnetic storage and many bioinspired applications because bulk $Fe_3O_4$ has a high Curie temperature($Tc={\sim}850K$) and nearly full spin polarization at room temperature(RT). In this work, $Fe_3O_4$ nanoparticles with different sizes of 12 to 15 nm were prepared in a well-controlled manner by a nonhydrolytic synthetic method. Here, we report the significant intergrain magneto-resistance(MR) of ${\sim}2%$ at RT in $Fe_3O_4$ nanoparticle pellets. The tunneling conductance was also investigated based on the Brinkman model, as well. Our results show clearly that the surface or interfacial property of the particles plays a crucial role in the MR effect.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.58-59
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• 2002

• Proceedings of the Korean Magnestics Society Conference
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• 2009.05a
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• pp.87-88
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• 2009

• Proceedings of the Korean Magnestics Society Conference
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• 2000.05a
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• pp.122-123
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• 2000

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.231-235
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• 2005

We studied the microstructural evolution of ZrTM-Al (TM=Nb and Ti) alloy films, MR and electrical properties of the MTJ with $ZrTM-AlO_x$ barrier as a function of Zr/TM ratio. We observed that the ternary-oxide barrier reduced the TMR ratio due mainly to the structural defects such as the surface roughness. The change in TMR ratio and $V_h$ with Zr/TM ratio exactly corresponds to the systematic changes in the microstructural variation. Although the MTJ with ternary oxide reduced the TMR and the electrical stabilities, the junction resistances decreased as the Ti and Nb concentration increased due to the band-gap reduction caused by the formation of extra bands

• Journal of the Korean Magnetics Society
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• v.12 no.5
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• pp.168-173
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• 2002

Electrostatic discharge characteristics were studied by connecting human body model (HBM) with tunneling magnetoresistance (TMR) device in this research. TMR samples were converted into electrical equivalent circuit with HBM and it was simulated utilizing PSPICE. Discharge characteristics were observed by changing the component values of the junction model in this equivalent circuit. The results show that resistance and capacitance of the TMR junction were determinative components that dominate the sensitivity of the electrostatic discharge(ESD). Reducing the resistance oi the junction area and lead line is more profitable to increase the recording density rather than increasing the capacitance to improve the endurance for ESD events. Endurance at DC state was performed by checking breakdown and failure voltages for applied DC voltage. HBM voltage that a TMR device could endure was estimated when the DC failure voltage was regarded as the HBM failure voltage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.141-155
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• 2023

Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.