• Journal of the Korean Magnetics Society
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• v.22 no.6
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• pp.228-233
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• 2012

Magnetic properties of a solid are determined by the quantum mechanical states of valence electrons. Spin-polarized angle-resolved photoemission spectroscopy (SP-ARPES) is a powerful tool to probe the electronic states in a solid and provides valuable information on magnetic properties of a solid. In this article, brief introduction to SP-ARPES and its applications are provided.

• Journal of the Korean Magnetics Society
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• v.17 no.5
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• pp.194-197
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• 2007

Understanding the spin polarization (P) has been an ongoing research challenge. The $Co_{1-x}Mn_x$ (x=0.27, 1) and $Co_{1-x}Fe_x$ (x=0, 0.5, 1) films were prepared using UHV-MBE system. For these films, the magnetic properties and spin polarization were investigated using SQUID and Meservey-Tedrow technique, respectively. Although measured P is uncorrelated to the bulk magnetic moment (M) in Co-Fe and Ni-Fe alloy films, it correlates with M in some alloys such as Co-Mn and Ni-Cu. The results can be understood by the tunneling currents made up of the hybridized sp-d electrons near the Fermi-energy level. Our work shows the feasibility to tailor new materials with large P values.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.137-138
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• 1997

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.111-111
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• 2006

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.118-118
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• 2013

• Journal of the Korean Magnetics Society
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• v.19 no.4
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• pp.133-137
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• 2009

$MnGeP_2$ thin films grown on GaAs exhibit room-temperature ferromagnetism with $T_C{\sim}$320 K, based on both magnetization and resistance measurements. The coercive fields at 5, 250, and 300 K are 3870, 1380 and 155 Oe, respectively. The anomalous Hall effect was observed, indicating spin polarization of the carriers. Hysteresis has been observed in both magnetoresistance and Hall measurements. The current-voltage characteristics of a $MnGeP_2$ film grown on an n-type GaAs substrate display semiconducting behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1056-1060
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• 2005

We investigated the fabrication and characteristics of the nitride-based spin-polarized LEDs with room-temperature ferromagnetic (Ga,Mn)N layer as a spin injection source. The (Ga,Mn)N thin films having room-temperature ferromagnetic ordering were found to exhibit the negative MR and anomalous Hall resistance up to room temperature, revealing the existence of spin-polarized electrons in (Ga,Mn)N films at room temperature. The electrical characteristics in the spin LEDs did not degraded in spite of the insertion of the (Ga,Mn)N layer into the LED structure. In EL spectra of the spin LEDs, it is confirmed that the devices produce intense EL emission at 7 K as well as room temperature. These results are expected to open up new opportunities to realize room-temperature operating semiconductor spintronic devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.150-152
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• 2005

We investigated the fabrication and characteristics of spin-polarized LEDs based on GaN using (Ga,Mn)N as spin injection source. (Ga,Mn)N thin films were found to exhibit the ferromagnetic ordering above room temperature and the negative MR up to room temperature. The electrical characteristics in spin LEDs did not degraded in spite of the insertion of (Ga,Mn)N films. In EL spectra of spin LEDs, it is confirmed that spin LEDs emit the strong light at 7 K as well as room temperature. These results suggest that it is possible to emit spin-polarized light in our spin LEDs.

• Journal of the Korean Magnetics Society
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• v.17 no.5
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• pp.210-214
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• 2007

Recent years have seen a rapid development of spintronics. One of the major achievements of this field is the understanding of spin dependent process in various physical systems, for example, metallic multilayers showing the giant magnetoresistance (GMR). Today devices based on the GMR are revolutionizing electronic data storage. In this paper, we review recent developments in the research on GMR of low dimensional structures. We describe the magnetoresistance properties of magnetic multilayers, multilayered nanowires and nonopillars, etc.

• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.184-187
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• 2013

The influence of insertion of an ultra-thin Cu-Phthalocyanine (CuPc) between MgO barrier and ferromagnetic layer in magnetic tunnel juctions (MTJs) was investigated. In order to understand the relation between the electronic and structural properties of Fe${\backslash}$MgO${\backslash}$CuPc, the surface (or interface) analysis was carried out systematically by using spin polarized metastable He de-excited spectroscopy for the CuPc films grown on the Si(001)${\backslash}$5 nm MgO(001)${\backslash}$7 nm Fe(001)${\backslash}$1.6 nm MgO(001) multilayer structure as the thickness of CuPc increases from 0 to 5 nm. In particular, for the 1.6 nm CuPc surface, a rather strong spin asymmetry between up- and down-spin band appears while it becomes weaker or disappears for the CuPc films thinner or thicker than ~1.6 nm. Our results emphasize the importance of the interfacial electronic properties of organic layers in the spin transport of the hybrid MTJs.