visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2023-01-11 11:00 
일시  
장소 E6-2 #1323 
연사 Sangjun Kang 
물리학과 양용수 교수님 연구실에서 한국과학기술연구원(KIST) 강상준 박사님을 초청하여,
로렌츠-주사투과전자현미경을 이용한 유연한 강자성체의 자기-탄성 결합에 대한 직접 관측에 대한 세미나를 아래와 같이 개최하고자 합니다.
구성원 여러분들의 많은 관심과 참여 부탁 드립니다.
 
* Title: Directly proving magnetoelastic coupling in a soft ferromagnet using Lorentz 4D-STEM

* Speaker: Sangjun Kang (KIST)   강상준 박사

* Date: 11am, 11th January 2023 (Wednesday)

* Place: E6-2 1323 (no zoom broadcasting)

Abstract:
Soft ferromagnetic materials, e.g. silicon ferrites and Fe-based amorphous alloys, play a major role in the conversion of energy owing to their high energy efficiency and power density [1]. Their magnetic structure consists of domains, where the magnetic dipoles are aligned to minimize the magnetostatic energy. The resulting magnetic structure is highly sensitive to local variation in the atomic spacing, i.e., atomic strain, of the materials due to magnetoelastic coupling through magnetocrystalline anisotropy (K_c) and stress anisotropy (K_σ) [2]. The anisotropy contributions raise coercivity (H_c) by restricting domain wall motions. In particular, for Fe-based amorphous alloys, which originally possess an isotropic atomic structure and extremely low H_c, the magnetic properties are extremely sensitive and usually deteriorated to the imposed stress [3]. This can be critical for their application in magnetoelectric machines, e.g. induction motors, which can be mechanically stressed during usage. To understand fundamental magnetism, e.g. magnetoelastic coupling, as a basis to design new materials, correlative measurements of the magnetic and atomic structure of soft ferromagnetic materials are desired.
We have developed Lorentz 4-dimensional scanning transmission electron microscopy (Ltz-4D-STEM) for correlative mapping of the magnetic structure, strain fields, and relative packing density and applied this approach to deformed Fe-based metallic glasses as illustrated in Figure 1. Our approach considers the momentum transfer of the electron beam due to the local magnetic field, the elliptic distortion of the amorphous diffraction ring under strain, and the area encompassed by the ring to quantify the relative atomic density and reveal their spatial-correlative variance [4]. This enables a direct pixel-level correlation of the magnetic and atomic structure and thus experimentally maps the magnetoelastic energy of soft ferromagnets. This method opens a new door to studying magnetic materials.
 

[1] Li et al., Progress in Materials Science 103, 235-318 (2019)

[2] Silveyra et al., Science 362, 418 (2018)

[3] Shen et al., Nat. Commun. 9, (4414), 2018

[4] Kang et al, Nat. Commun, Under review. Currently available at Nature portfolio https://doi.org/10.21203/rs.3.rs-1545335/v1 (2022)

Attached: C.V

 

번호 날짜 장소 제목
302 2022-11-17 16:00  E6-2 #1323  (광학분야 세미나) Ultrastructural and Spectroscopic Studies by Super-Resolution Fluorescence Microscopy
301 2023-01-11 16:00  E6-2 #1323  Non-abelian anyons and graph gauge theory on a superconducting processor, Eun-Ah Kim (Cornell University/Ewha Womans University)
300 2023-05-12 11:00  E6-2 #1323  (응집물리 세미나)Interlayer conductivity and plasmon in weakly coupled layered systems
299 2024-01-24 15:00  E6-2 #1323  Determination of single molecule loading rate during mechanotransduction file
298 2022-09-22 16:00  E6-2 #1323  (광학분야 세미나) Quasi-particle-like optical vortices in magnetic materials
297 2023-04-14 12:00  E6-2 #1323  (응집물리 세미나)Exotic quantum phenomena in two-dimensional materials file
» 2023-01-11 11:00  E6-2 #1323  Directly proving magnetoelastic coupling in a soft ferromagnet using Lorentz 4D-STEM file
295 2023-01-12 14:40  E6-2 #1323  JILA 1D Wannier-Stark optical lattice clock file
294 2022-11-11 11:00  E6-2 #1323  [Update 세미나영상] (응집물리 세미나) Honeycomb oxide heterostructures for quantum spin liquid file
293 2023-03-17 11:00  E6-2 #1323  (응집물리 세미나)Operando electron microscopy investigation of domain dynamics in twisted van der Waals materials file
292 2023-05-18 16:00  E6-2 #1323  (광학분야 세미나)Dielectric metasurfaces for optimized optical system and spatial light modulators
291 2023-05-19 11:00  E6-2 #1323  (응집물리 세미나)Dipole condensations in Tilted Bose-Hubbard Chains
290 2022-10-27 16:00  E6-2 #1323  (광학분야 세미나) Cavity optomechanical systems for quantum transduction
289 2022-10-07 11:00  E6-2 #1323  [Update 세미나 영상] (응집물리 세미나) Competing orders in a vanadium-based kagome metal monolayer file
288 2023-09-07 12:00  E6-2 #1323  2023 가을학기 광학분야 및 응집물리 특별세미나 전체 일정 file
287 2023-05-26 11:00  E6-2 #1323  (응집물리 세미나)Spectral Analyses of Stochastic Charge Trapping in Oxide Heterostructures file
286 2022-09-23 11:00  E6-2 #1323  [Update 세미나 영상] (응집물리 세미나) Steady Floquet-Andreev states in graphene Josephson junctions file
285 2022-12-07 16:00  E6-2 #1323  (광학분야 세미나) Non-Hermitian physics and non-Hermitian singularity
284 2022-10-13 16:00  E6-2 #1323  (광학분야 세미나) Ultrafast Optics for Ultra-Precision Metrology and Realization of Flexible/Stretchable Laser-Induced-Graphene Electronics
283 2024-03-08 11:00  E6-2 #1323  2024 봄학기 광학분야 및 응집물리 특별세미나 전체 일정 file