Seongcheol Noh

nsc0316@gmail.com

nsc0316@kaist.ac.kr

Education

2021~ : Samsung Electronics
2016~2021: KAIST, Ph.D candidate, EE
2014~2016: KAIST, MS, EE
2011~2014: KAIST, BS, Physics
2008~2011: Korea Science Academy of KAIST

Research

Topic: Quantum Transport in Spintronic Devices

1. Analysis of magnetic tunnel junction (MTJ) structure using non-equilibrium Green's function (NEGF) method

2. Spin dynamics analysis in MTJ structure

NEGF-LLGS self-consistent calculation

Motivation
- Electron spins had been ignored in conventional electronics, but today this field of research is exapanding considerably.
- Spin-transfer torque (STT) is based on quantum mechanic effect, in which orientation of magnetic layer can be modified by angular momentum transfer.
- Spin-transfer torque magnetic random access memory (STT-MRAM) with MgO-MTJ is now considered as one of the promising candidates for future memory device.
Methodology
- We exploit non-equilibrium Green's function (NEGF) method to describe quantum transport in such a nano-scaled electric device.
- For the successive analysis of dynamic picture of MTJ, we solved Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation combining with NEGF.

3. Two-dimensional micromagnetic simulator development

Example: "Step" cross-tie shape
- (Animated-gif => click the image)

(Rectangular shape)

(Arbitrary shape)

Spin torque calculation
Landau-Lifshitz-Gilbert (LLGS) equation

4. Synthetic antiferromagnetic free layer-based device

5. Strain effect study on MTJ stack

Stain effect on the magnetic anisotropy
Materials
- Co_{x}Fe_{1-x} alloy
- Heusler alloy
Simulation methodology
- VASP - relaxation and MAE calculation
- Siesta + Smeagol - DFT-NEGF calculation
- in-house tools - transport calculation

Research Interests

Quantum Transport
Spintronics

Publications

Journal

1. Seongcheol Noh, Doo Hyung Kang, and Mincheol Shin,

"Simulation of Strain Assisted Switching in Synthetic Antiferromagnetic Free Layer-Based Magnetic Tunnel Junction",

IEEE Transactions on Magnetics, vol. 55, no. 4, pp. 1-5, Apr. 2019.

2. Seongcheol Noh, Stefano Sanvito, and Mincheol Shin,

"DFT-NEGF Simulation Study of Co2FeAl-MgO-Co2FeAl Magnetic Tunnel Junctions Under Biaxial Strain",

IEEE Transactions on Magnetics, vol. 58, no. 5, Mar. 2022.

Selected Conference

1. Seongcheol Noh and Mincheol Shin, "Quantum transport simulation of spin-transfer torque (STT):

nonequilibrium Green's function approach", KCS, Incheon Korea Republic, 2015.

2. Seongcheol Noh and Mincheol Shin, "Analysis of Magnetization Reversal in Magnetic Tunnel junctions with

Self-consistent Calculation", AWAD, Jeju Korea Republic, 2015.

3. Seongcheol Noh, Joon-Ho Lee, and Mincheol Shin, "Magnetic Tunnel Junction-Based Spin-Torque Oscillator Simulation: NEGF-LLGS Approach", ISPSA, Jeju Korea Republic, 2016.

4. Seongcheol Noh, Doo Hyung Kang, and Mincheol Shin, "Theoretical study of strain-assisted synthetic

anti-ferromagnetic layer based magnetic tunnel junction switching", ISPSA, Jeju Korea Republic, 2018.

5. Seongcheol Noh, Doo Hyung Kang, and Mincheol Shin, "Simulation of strain-assisted switching in antiferromagnetically coupled synthetic free layer-based magnetic tunnel junction", NANOKOREA, KINTEX Korea Republic, 2019.