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 1057362
681 2019학년도 2학기 콜로퀴움 일정 2019.07.17 424534
680 <12/3> Magnetic couplings, optical spectra, and spin-orbit exciton in 5d Mott insulator Sr2IrO4 2012.11.26 358494
679 <Mar.3(Wed.)>Scaling laws in Natural Language Processing 2021.02.25 316618
678 2017학년도 1학기 콜로퀴움 일정 2017.01.05 283012
677 <10/25> Wave properties of dipole-exchange spin waves in confined magnetic thin films 2006.10.25 263946
676 2020학년도 1학기 콜로퀴움 일정 2020.01.31 253179
675 <5/16> 물리학자가 바라 본 단백질: 왜, 어떻게 연구하는가? 2012.05.10 251648
674 BK 석학초청 특별세미나 - Frustration and dimensional reduction in multi-orbital systems 2011.10.28 236168
673 <3/14>Adaptive Optics for the Human Eye and Ophthalmic Applications 2008.03.12 234779
672 <11/6> Graphene plasmon and Plasmonics 2013.10.31 234722
671 <6/11> Advanced Physiological Optics and Its Ophthalmic Applications 2014.05.28 229960
670 <8/30(Wed.)10:30>​Technology convergence and applications of Large-Area Electronics, e-Textiles, bio-sensors and bio-electronics 2017.08.29 227731
669 <6/17> Oscillating Fuzzy Sphere and M5/anti M5 configurations in ABJM model 2009.06.16 226338
668 <12/21> Special Seminar by Professor Ilya Vekhter 2010.11.30 226216
667 <Jan.14(Thu.)>Oxygen sponge effects for epitaxial manganite thin film design 2021.01.11 215125
666 <5/16(토)> 세미나 개최 안내 2015.05.18 205906
665 <11/5(화)> 특별세미나 개최 안내 2013.11.01 205195
664 <June.12(Wed.)> Ribocomputing: Cellular Logic Computation using RNA Devices file 2019.06.07 198615
663 <Sep. 23(Wed.) 4:30 PM>Grain boundary effect in Metal : A journey of discovery from crystal to thin films without grain boundaries 2015.09.16 197038