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
543 2024-06-03 11:00  E6, #3441  New high Tc superconductivity and symmetric pseudogap metal in the bilayer nickelate La3Ni2O7-Part1 file
542 2024-05-30 10:00  E6-2, #2501  Quasiperiodic Effects in Quasicrystals
541 2024-05-29 16:00  E6-2, #2502  [High Energy Theory Seminar] Amplitudes Meet Cosmology: From Inflation to the Large-Scale Structure
540 2024-05-28 11:00  E6-2, #2501  동적평균장 이론 소개
539 2024-05-28 10:00  E6-2, #2501  Mixed-State Quantum Spin Liquids and Dynamical Anyon Condensations in Kitaev Lindbladians
538 2024-05-16 16:00  E6-2, #1323  [High Energy Theory Seminar] Conformal Collider Physics
537 2024-05-16 14:30  E6-2 #2502 & Zoom  [Astrophysics Seminar] Observational Cosmology with Superconducting Sensors
536 2024-05-14 16:00  E6-2, #2502  [High Energy Theory Seminar] Minimal Production of Prompt Gravitational Waves during Reheating.
535 2024-05-08 16:30  E6-2 #2502  [High Energy Theory Seminar] Black Holes from Heavy Operators in N=4 SYM
534 2024-05-01 16:00  E6-2 #2502  [High Energy Theory Seminar] Across the Mass Spectrum: Utilizing Small-Scale Structures to Probe Dark Matters
533 2024-04-19 15:00  E6-1, #1501  Engineering Physics for Semiconductor Equipment Innovation file
532 2024-04-11 16:00  E6-2, Rm#1323  Theoretical Studies of the Electric Field Induced Thermal Hall Effect in the Quantum Dimer Magnets XCuCl3 (X = Tl, K)
531 2024-03-28 11:00  E6, #2501  Geometric characterization of thermoelectric performance of two-dimensional quadratic band-crossing semimetals
530 2024-03-27 16:00  E6-2, #2502  [High Energy Theory Seminar] The Callan Rubakov Effect
529 2024-03-20 16:00  E6-2 #2502  [High-Energy Theory Seminar] Black hole states at finite N
528 2024-03-13 16:00  E6-2 #2502  [High-Energy Theory Seminar] The Schwarzschild Black Hole from Perturbation Theory to all Orders
527 2024-03-08 11:00  E6-2 #1323  2024 봄학기 광학분야 및 응집물리 특별세미나 전체 일정 file
526 2024-03-07 16:00  Zoom  [CAPP seminars] Development of Superconducting Transition Edge Sensors at SRON file
525 2024-02-26 16:00  E6-1 #1501  2024 봄학기 콜로키움 전체 일정 file
524 2024-02-16 10:00  E6, #1323  Optical conductivity of superconducting states driven by Van Hove singularities