korean english


Home > 게시판 > 세미나

위상양자물성 연구실에서 Materials Science and Technology Division, Oak Ridge National Laboratory의 도승환 박사님을 초청하여 아래와 같이 세미나를 개최합니다.

학과 구성원 여러분의 많은 참여를 부탁 드립니다.


○ Topic: Longitudinal magnon decay in the quasi-two-dimensional antiferromagnet in Ba2FeSi2O7


○ Speaker: 도  승  환  박사님 (Materials Science and Technology Division, Oak Ridge National Laboratory)


○ Date/time: 2022. 5. 10. (Tue.) 4:00 PM


○ Place: Natural Science 1,  Room No. 31317


○ Abstract: An ongoing challenge in the study of quantum materials, is to reveal and explain collective quantum effects in spin systems where interactions between different mode types are important. This talk will focus on this problem through a combined experimental and theoretical study of interacting transverse and longitudinal modes in an S=1 easy-planar quantum magnet, Ba2FeSi2O7 [1,2]. Our inelastic neutron scattering measurements show that Ba2FeSi2O7 is a quasi-two-dimensional antiferromagnet with large single-ion anisotropy (D>5J), and the extended spin wave theory analysis demonstrates its close proximity to a quantum critical point. The measured spectrum reveals the emergence, decay, and renormalization of a longitudinal mode throughout the Brillouin zone. The decay of the longitudinal mode is particularly pronounced at the zone center where the decay channels to the transverse modes are most active. A generalization of the standard spin-wave theory is used to account for the many-body effects of the interacting transverse and longitudinal modes in Ba2FeSi2O7. The measured mode decay and renormalization are reproduced by including one-loop corrections, where the kinematic conditions for the interactions are satisfied. Finally, the kinematic condition becomes violated in magnetic field. Our field inelastic neutron scattering measurement reveals that the longitudinal mode evolves into a long-lived quasi-particle in magnetic fields, demonstrating that this quantum many-body effect is tunable [3].

[1] S.-H. Do, H. Zhang, et al., Nat. Commun. 12 5331 (2021)
[2] T.-H. Jang, S.-H. Do et al., PRB 104 214434 (2021)
[3] S.-H. Do et al., (in preparation)

번호 제목 날짜 조회 수
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 1057533
296 <July 8(Fri.)>Intertwined magnetism and charge density wave in a kagome metal 2022.06.03 887
» <May. 10(Tue.)>Longitudinal magnon decay in the quasi-two-dimensional antiferromagnet in Ba2FeSi2O7 2022.05.09 1266
294 <May. 3(Tue.)>Anomalous Hall signatures of nonsymmorphic nodal lines in the doped chromium chalcospinel CuCr2Se4 2022.04.19 1384
293 <Jan. 27(Thu.)>Emulating twisted double bilayer graphene with a multiorbital optical lattice 2022.01.18 2277
292 <Nov. 29(Mon.)>Exploring light-matter interactions at atomic scale using electron microscopy 2021.11.22 6528
291 <July 21(Wed.)> Strongly Correlative Ionics 2021.07.19 22048
290 <Aug. 6(Fru.)> Gravitationally probing dark matter (DM) microphysics 2021.08.03 25874
289 <June 23(Wed.)>Valley Polarization and Exciton Hall Effect in Transition Metal Dichalcogenides 2021.06.22 26680
288 <8/1(Sat.)> Recent Advances in Deep Learning 2020.07.29 30646
287 <Nov. 5(Fri.)>Strongly Coupled Moire Photonics 2021.11.01 35907
286 <July 14(Wed.)> B1g phonon anomaly driven by Fermi surface instability at intermediate temperature in YBa2Cu3O7−δ 2021.07.13 36617
285 <June 01(Tue.)>Frustration-induced Athermal Behaviors: Hilbert Space Fragmentation and Quantum Many-Body Scars 2021.05.24 37739
284 [8/1(Wed.), 8/2(Thu)] Lectures on gravitational waves 2018.07.24 43740
283 <9/24(Tue) 4:00 pm ~ > Structure Formation with Two Periods of Inflation: Beyond plain LCDM 2019.09.17 48400
282 <11/6(Tue.) 3:00pm>The Surprising Solar Gamma-ray Emission from Cosmic-Ray Interactions 2018.11.03 48809
281 <4/5(Wed.) 18:00pm> 저에너지 가속기의 활용 2017.04.05 49071
280 <7/11(Wed.) 3:00pm> Traversable wormholes: two-dimensional example 2018.07.09 51168
279 <11/12(Mon.) 3:30pm>Dark Matter Probes with Astrophysical Observations 2018.11.05 51968
278 <6/21(Thu.) ~ 22(Fri.)>Mini-workshop for the entanglement entropy at SKKU 2018.06.18 52266
277 <11/23(Fri.) 11:00am>Barrier-bound States in Flat-band Systems 2018.11.19 52336