http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Chun-Yeol You,Hyungsuk Kim 한국자기학회 2013 Journal of Magnetics Vol.18 No.4
We find a metastable vortex state of the perpendicular magnetic anisotropy free layer in spin transfer torque magnetic tunneling junctions by using micromagnetic simulations. The metastable vortex state does not exist in a single layer, and it is only found in the trilayer structure with the perpendicular magnetic anisotropy polarizer layer. It is revealed that the physical origin is the non-uniform stray field from the polarizer layer.
Micromagnetic Simulations for Spin Transfer Torque in Magnetic Multilayers
Chun-Yeol You 한국자기학회 2012 Journal of Magnetics Vol.17 No.2
We investigate spin transfer torque (STT) in magnetic multilayer structures using micromagnetic simulations. We implement the STT contribution for magnetic multilayer structures in addition to the Landau-Lifshitz-Gilbert (LLG) micromagnetic simulators. In addition to the Sloncewski STT term, the zero, first, and second order field-like terms are also considered as well as the effects of the Oersted field due to the running current are addressed. We determine the switching current densities of the free layer with the exchange biased synthetic ferrimagnetic reference layers for various cases.
Spin Torque Nano-Oscillator with an Exchange-Biased Free Rotating Layer
Chun-Yeol You 한국자기학회 2009 Journal of Magnetics Vol.14 No.4
We propose a new type of spin torque nano-oscillator structure with an exchange- biased free rotating layer. The proposed spin torque nano-oscillator consists of a fixed layer and a free rotating layer with an additional anti-ferromagnetic layer, which leads to an exchange bias in the free rotating layer. The spin dynamics of the exchange-biased free rotating layer can be described as an additional exchange field because the exchange bias manifests itself by the existance of a finite exchange bias field. The exchange bias field plays a similar role to that of a finite external field. Hence, microwave generation can be achieved without an external field in the proposed structure.
Dependence of the switching current density on the junction sizes in spin transfer torque
You, Chun-Yeol,Jung, Myung-Hwa American Institute of Physics 2013 JOURNAL OF APPLIED PHYSICS - Vol.113 No.7
<P>We investigate the dependence of switching current density on the junction sizes in the in-plane spin transfer torque nanopillar structures by using micromagnetic simulations. While the macrospin model predicts weak dependence of switching current density on the junction sizes, we find that the switching current density is a sensitive function of the junction sizes. It can be explained with the complicated spin configurations and dynamics during the switching process. The detail spin configurations and dynamics are determined by spin wave excitation with the finite wave vector, which is related with the exchange coupling energy and junction shape. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4792728]</P>
You, Chun-Yeol,Kim, Hyungsuk IEEE 2017 IEEE transactions on magnetics Vol.53 No.11
<P>We investigate the effect of tunneling magnetoresistance (TMR) on the spin transfer-torque (STT) switching behaviors in magnetic tunneling junctions. In most of the micromagnetic simulations for STT switching, a uniform current density has been assumed, which is not realistic in the high TMR devices. The local STT is proportional to the local current density, and the local current density will be determined by the local resistivity. Since higher than 150% of TMR values is required in the real STT-magnetoresistive random access memory devices, the local resistance is dramatically changed as a function of the relative spin orientation between the fixed and free layers under the constant voltage operation mode. By employing non-uniform current density in STT switching simulations using the 'embedded object-oriented micromagnetic framework' scheme, we found that the details of switching behaviors such as switching time and critical current density are significantly influenced by the TMR values.</P>
Non-Equilibrium Green Function Method in Spin Transfer Torque
Chun-Yeol You 한국자기학회 2007 Journal of Magnetics Vol.12 No.2
We investigate the spin transfer torque in metallic multilayer system by employing Keldysh non-equilibrium Green function method. We study the dependences of the spin transfer torque on the detailed energy configuration of ferromagnetic, spacer, and lead layers. With Keldysh non-equilibrium Green function method applied to a single band model, we explore spin transfer torque effect in various layer structures and for various material parameters.