korean english


Home > 게시판 > 세미나

○ 일시: 7월 12일(화) 오전 11:00

○ 장소: 기초과학연구소 세미나실 (31317호)

○ 연사: 이  상  현  박사님 (High Energy Accelerator Research Organization (KEK) )

Title: Spin-direction-dependent magnetoelastic coupling on MnO, CoO, and NiO

○ Abstract: 

High resolution time-of-flight neutron diffraction and group theory resolved not only the long-standing problems of magnetic structure and phase transition mechanism in MnO, CoO, and NiO but also the issue of general symmetry in magnetic moment [1, 2]. Exchangestriction and new magnetostriction, so-called dipolar-magnetostriction and roto-magnetostriction, that induce phase transition from paramagnetic rocksalt structure to common C2/m monoclinic structure with magnetic propagation vector km=(0 1 0.5). We classify those into two groups by Γ1+(Ag)=(0, My, 0) and Γ2+(Bg)=(Mx, 0, Mz) spin direction in the order-parameter vector diagram. Time-reversal symmetry breaking causes discontinuous phase transition with linear-quadratic coupling Δβ~M2 between monoclinic angle Δβ and magnetic moment M. However, CoO and NiO show continuous phase transition with linear-cubic coupling Δβ~M3 forbidden by time-reversal symmetry. To the best of our knowledge, this is first experimental evidence that both magnetic moment and structural distortion can belong to same irreducible representation. Time-reversal symmetry prohibits same irreducible representation between them. The experimental results open a way to find new physics forbidden by time-reversal symmetry in condensed matter physics and material science.

번호 제목 날짜 조회 수
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 1089718
256 <1/16> Higgs-to-diphoton rate in type II seesaw models 2013.01.11 76918
255 <Nov.20(Wed.)>At the End of Space and Time: Imaging the Black Hole in M 87 2019.11.14 76908
254 <12/17(Tue.)> Nuclear spectroscopy with low energy reaction thermal neutrons in ILL 2019.12.17 76883
253 <11/14> 한방의료기기에서 나노소자의 활용 2008.11.11 76854
252 <4/7> Structure and Dynamics of Complex Networks 2006.04.03 76730
251 <4/6> Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment 2012.04.04 76684
250 <10/28> Magneto-electric response of multiferroic chiral magnets 2013.10.21 76320
249 <3/28> Nanoscale Physics related to Resistance Switchings &Its Applications to Resistance RAM 2008.03.24 76217
248 <12/12> 나노물리학과 컴퓨터 시뮬레이션 2008.12.08 76123
247 <9/7> On Dark Matter and its indirect detection with box-shaped gamma-rays 2012.09.05 75968
246 <Nov. 25(Wed.) 4:30 PM> Present and Future of OLED 2015.11.19 75956
245 <3/19> 고자기장 하에서 반도체 양자구조의 광전이 특성 2014.03.13 75950
244 <12/21>나노 광전소자 2006.12.31 75811
243 <May.15(Wed.)> Three-body problems and three-body forces in Classic and Quantum Systems 2019.05.08 75773
242 <6/3(수) 오후4:30분> The Quest for Dark Matter: Discovering Its Nature Underground? 2015.05.28 75743
241 <6/15(Fri.) ~ 16(Sat.)> Formation of first star and galaxy, Gravitational waves from Binary Mergers of Sub-Solar Mass Dark Black Holes 2018.06.12 75667
240 <9/22(Thu.) 10:30> Bulk-boundary correspondence from the inter-cellular Zak phase 2016.08.29 75548
239 <March. 16(Wed.) 4:30 PM> 초고속반도체의 블랙다이아몬드™,low-k 2016.03.10 75527
238 <3/30> Extreme Energy, Extreme Universe (Search for Ultra High Energy Particles in Space) 2007.03.26 75495
237 THINKING PHYSICS 발표회 2009.03.16 75197