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
511 2023-11-22 16:00  E6-2, #2502  [High Energy Theory Seminar] Renormalization and the Hierarchy Problem
510 2023-11-22 10:00  E6-2, #5301 & zoom  [High Energy Theory Seminar] Exact Quantum Algorithms to Recognize Quantum Phases of Matter
509 2023-11-16 16:00  E6-2(Natural Science B/D). 1st fl. #1323  Electric-field control of emergent phenomena in correlated oxide thin films
508 2023-11-15 16:00  E6-6, #119  Quantum hydrodynamic theory for plasmonics: from molecule-coupling to nonlinear optics
507 2023-11-09 16:00  E6-2(Natural Science B/D). 1st fl. #1323  Assessing the Capability of Near-Term Photonic Devices Towards Quantum Supremacy
506 2023-11-08 10:00  E6-2,#2502 & zoom  [High Energy Theory seminar] The Vacuum Sector of Asymptotically Isometric Codes
505 2023-11-01 16:00  E6-2, #2502  [High Energy Theory Seminar] Modular functions and 3D N=4 rank-zero superconformal field theories
504 2023-10-19 11:00  E6-2 #1322  Emergent functionalities of iridium oxide films with different growth orientation file
503 2023-10-11 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP seminar] Particle Physics with Neutrinos file
502 2023-10-11 16:00  E6-2, Rm2502  [High Energy Theory Seminar] Axion Magnetic Resonance
501 2023-10-04 16:00  E6-2, #2502  [High-Energy Theory Seminar] Moving towards quantum technologies: the case of quantum batteries
500 2023-09-27 16:00  E6, Rm#2501  Chiral Magnets: Domain-Wall Skyrmions and String Theory Realization
499 2023-09-26 16:00  E6-2, #2502  [High Energy Theory Seminar]A new step in interacting dark sector cosmologies
498 2023-09-21 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP seminar] Axion Magnetic Resonance file
497 2023-09-18 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP Seminar] Searching for axions in quantum vacuum birefringence file
496 2023-09-18 11:00  E6-2, #1322  Magic polarisation trapping of polar molecules for tunable dipolar interactions file
495 2023-09-14 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP seminar] Dark matter searches in Water Cherenkov Detectors file
494 2023-09-13 16:00  E6-2, #2502  [High Energy Theory Seminar] Cosmic Birefringence from Dark Photon
493 2023-09-07 12:00  E6-2 #1323  2023 가을학기 광학분야 및 응집물리 특별세미나 전체 일정 file
492 2023-08-29 16:00  E6-2, #2502  [High Energy Theory Seminar] Towards string loop corrections in Calabi-Yau orientifold compactifications.