• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.11-21
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• 2012

The line-width of carbon nanotubes (CNTs) was studied as a function of the temperature at a frequency of 9.49 GHz in the presence of external electromagnetic radiation. The relative frequency dependence of the absorption power is obtained with the projection operator technique (POT) proposed by Kawabata. The line-width increased as the temperature increased in the high-temperature region (T>200 K). The scattering is little affected in the low-temperature region (T<200 K) because there is no correlation between the resonance field and the Fermi-Dirac distribution function. Thus, the present technique is considered to be more convenient to explain the resonant system as in the case of other optical transition problems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1050-1053
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• 2001

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/HiO(300$\AA$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in 45$^{\circ}$Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) was shown in the range of about $\pm$50 Oe.

• Journal of Magnetics
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• v.15 no.3
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• pp.132-137
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• 2010

Plasma etching of $SiO_2$ contact holes was statistically analyzed by a fractional factorial experimental design. The analysis revealed the dependence of the etch rate and DC self-bias voltage on the input factors of the magnetically enhanced reactive ion etching reactor, including gas pressure, magnetic field, and the gas flow rates of $CHF_3$, $CF_4$, and Ar. Empirical models of the DC self-bias voltage and etch rate were obtained. The DC self-bias voltage was found to be determined mainly by the operating pressure and the magnetic field, and the etch rate was related mainly to the pressure and the flow rates of Ar and $CHF_3$.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.37-40
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• 2001

The semiconductor's design rule becomes more stringent, hence the silicon-dioxide etching technique is important issue. In this work we compared the etching characteristics of different three types of Plasma source, Normal ICP, magnetized ICP and E-IC $P^{TM}$. The E-IC $P^{TM}$ source shows higher etch rate at lower pressure and this is advantageous for the fine pattern process. The etching characteristics were varied with external magnetic field frequency at I-lCP and this is examined with Nanospe $c^{TM}$ and SEM. We designed Langmuir probe system for time resolved diagnosis. ion density of E-ICP is varying periodically with the applied external magnetic field frequencyquency

• Journal of Magnetics
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• v.6 no.1
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• pp.1-4
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• 2001

We have used acetic acids ethanol and distilled water as a solvent to synthesize $La_{2/3}Sr_{1/3}Mn_{0.99}{^{57}}Fe_{0.01}O_3$(LSMFO) precursor. Crack-free LSMFO granular polycrystalline thin films have been deposited on thermally oxidized silicon substrates by spin coaling. The dependence of crystallization, surface morphology, magnetic and transport properties on annealing temperature was investigated. With increasing annealing temperature, the metal-semiconductor (insulator) transition temperature and the magnetic moment decrease while the resistivity increases. The lattice constants remain almost unchanged. For LSMFO thin films, spin-dependent interfacial tunneling and/or scattering magnetoresistance were observed. Our results indicate that the annealing temperature is very important in determining the intrinsic and extrinsic magnetotransport properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.195-198
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• 1996

In conducting systems based on LB films, TCNQ derivatives have been extensively studied as electron acceptor molecules. We have investigated the optical, electrical, and magnetic properties of Viologen-(TCNQ￣)$_2$LB films. In UV/visible absorption measurements, we have observed TCNQ￣ peak at 380 nm and dimer peak at 620 nm. The electron spin resonance measurements infer that Viologen-(TCNQ￣)$_2$LB film exhibits anisotropic properly. In other words, the LB film shows angular dependence. Iodine doping affects the degree of charge transfer and the conductivity of the films. The UV/visible absorption spectra of the LB film doped with I$_2$show peaks at near 400~430 nm and there is no dimer absorption peak. The in-plane electrical conductivity of the undoped film is approximately 4.2$\times$10$^{-6}$ S/cm.

• Journal of Magnetics
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• v.10 no.2
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• pp.63-65
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• 2005

The $^1H$ NMR spin-lattice relaxation in a series of the organic-inorganic hybrid systems $(C_nH_{2n+1}NH_3)_2SnCl_6$ (n = 8, 10, 12, 14) undergoing two successive phase transitions was studied. A discontinuity characteristic of a first order phase transition was observed at the high-temperature conformational transition. Besides, the spin-lattice relaxation rate below the conformational transition temperature was well fitted by four types of molecular motions, from which the chain-length dependence of the activation energies of the molecular groups was obtained.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.259-261
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• 1999

In this paper, we investigated the frequency dependences of AC loss and the magnetic properties of a superconductor using magnetization method. We used the YBCO bulk superconductor sample which has a square-shaped cross sectional area of $6mm{\times}6mm$. and 43mm-long in axial direction. The applied AC magnetic field was parallel to the direction of sample axis. It is observed that YBCO bulk has the diamagnetic properties. AC loss calculation of YBCO bulk superconductor was performed by evaluating the total area of magnetization traces. We performed two cases of experiments, one for $B_m<B_p$ and the other for $B_m<B_p$. The experiments showed that the AC loss dependences on frequency were different in each mode, as was indicated in other publications.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.182-185
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• 2003

We have suggested an equivalent circuit model for switching performance of bipolar spin transistor composed of a nonmagnetic metal film (N) sandwiched between two ferromagnetic metal films (F1 and F2). The 'ON' or 'OFF' operation of this equivalent circuit model is simulated by depending on the orientation of the magnetization of F1 and F2 rather than the strength of the external magnetic filed. Changing the coupling coefficient, turn number of two inductances, (L1:L2) like a transformer, and parallel variable resistance R4 connected to L2 at the collector region, we can explain the magnetic characteristics and the dependence of magneto resistance ratio on the orientation of spin-polarized electrons.

• Journal of Magnetics
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• v.14 no.1
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• pp.31-35
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• 2009

Herein, the Magneto-Optical Kerr Effect (MOKE) signal enhancement in nanostructures in investigated. It is well known that the MOKE signals of ferromagnetic thin films are enhanced with an additional dielectric layer due to multiple reflections. The MOKE signal is modulated with the additional dielectric layer thickness and is at a maximum when reflectivity is at a minimum. This is not always true in the nanostructures due to the contribution from the non-magnetic substrate portion, especially when substrate reflectivity is minimized and the dependence of the additional dielectric layer thickness for the nanostructure is changed in the case of the continuous thin film. We showed that the MOKE signal for nanostructures could be enhanced with a properly designed, dielectric layer in addition to the anti-reflection coated substrates.