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
447 2021-02-15 17:00  Zoom  Magnetic Cluster Octupole Domain evolutation in chiral antiferromagnets file
446 2012-04-02 16:00  E6, 1501  A new route to ferroelectricity in magnetic spinels: a case of Co2MnO4
445 2020-12-10 13:55  Zoom  Consistency of Boltzmann equation and light dark matter from inflaton decay
444 2016-09-05 16:00  Natual Scien Bldg.(E6)m #1501  Physics Colloquium : 2016 Fall file
443 2021-01-28 15:00  Zoom  Topological Transport of Deconfined Hedgehogs in Magnets file
442 2018-12-26 16:00  E6-1. 3rd fl. #3434  Informal Workshop on Topology and Correlation file
441 2021-06-22 17:00  Zoom webinar  Spintronics meets Quantum Materials file
440 2021-06-08 10:00  Zoom webinar  Photonic crystal devices for sensing file
439 2023-06-30 11:00  E6-6 #1501  The Dual Mode Quantum Computer file
438 2023-11-29 10:00  Zoom  [High Energy Theory Seminar] Averaged null energy and the renormalization group
437 2020-09-14 17:30  Zoom webinar  KAIST Global Forum for Spin and Beyond (Third Forum) file
436 2022-11-03 13:00  E6-2 #1323  [High-Energy Theory Seminar] Supersymmetric observables via Fermi-gas method
435 2019-07-08 14:00  E6, #1322  Ultrabroadband squeezed pulses and their relation to relativity file
434 2023-04-05 16:00  E6-2, #2502  [High Energy Theory Seminar]Anomalies of Discrete 1-Form Symmetries in QCD-like Theories
433 2024-03-27 16:00  E6-2, #2502  [High Energy Theory Seminar] The Callan Rubakov Effect
432 2023-02-20 17:00  KI building (E4), Lecture Room Red (B501)  (Optics Seminar) Neural Holography for Next generation Virtual and Augmented Reality Displays file
431 2024-03-20 16:00  E6-2 #2502  [High-Energy Theory Seminar] Black hole states at finite N
430 2024-01-03 11:00  E6-2, #1323  Interplay of Strong Correlations, Topology, and Disorder in 2D Quantum Matters
429 2023-09-13 16:00  E6-2, #2502  [High Energy Theory Seminar] Cosmic Birefringence from Dark Photon
428 2022-06-23 11:00  E6 Room(#1322)  JILA’s search for the electron’s Electric Dipole Moment (eEDM) to probe physics beyond the standard model file