ABSTRACT
Neutron scattering is a unique experimental probe for the correlation functions of the atomic position and spin moment in broad momentum-energy space. Since the neutron scattering technique was applied to the study on antiferromagnetic order in MnO [1], it has made considerable progress and is now widely used in various fields of science. In this seminar, I will first review the status of neutron instruments in research reactor JRR-3. Following a 10-year shutdown due to the great earthquake in East Japan in 2011, JRR-3 restarted in 2021, leading to many publications. I will also discuss recent trend in the inelastic neutron scattering studies on magnetism, including topics such as Kitaev liquid, magnon polarization, topological quasiparticle, etc.
Secondly, I will present research on quantum magnetism conducted by my group. We observed hybridization of Higgs-amplitude and Goldstone modes in frustrated magnet CsFeCl3 under pressure using a combination of triple-axis and chopper spectrometers [2]. Subsequently, we studied the magnetic field effect on the isostructural compound RbFeCl3. Thorough the detailed analysis on the spectra, we found that the magnon lifetime was successfully controlled via the magnetic field [3]. I will also talk about chiral-split magnon in altermagnet MnTe [4], which was recently observed by inelastic neutron scattering technique.
Finally, I will introduce a newly developed multiplex triple-axis spectrometer, HODACA, located at the C1-1 beam port in JRR-3 [5]. Compared to a conventional triple-axis spectrometer, HODACA improves the measurement efficiency by a factor of 70.
[1] C. G. Shull and J. S. Smart: Phys. Rev. 76, 1256 (1949).
[2] S. Hayashida et al., Sci. Adv. 5, eaaw5639 (2019).
[3] S. Hasegawa et al., Nat Commun. 15, 125 (2024).
[4] Z. Liu et al., Phys. Rev. Lett. 133, 156702 (2024).
[5] H. Kikuchi et al., J. Phys. Soc. Jpn. 93, 091004 (2024).
BIOGRAPHY
Takatsugu Masuda graduated from Department of Applied Physics, The University of Tokyo in 1996. From 1999 to 2002, he was a research associate in Department of Applied Physics, University of Tokyo, and received a Ph.D. from University of Tokyo in 2002. From 2002 to 2005, he worked as a postdoctoral researcher at Oak Ridge National Laboratory. He worked as an associate professor at Yokohama City University from 2005 to 2010. In 2010, he joined Institute for Solid State Physics, University of Tokyo as an associate professor. Currently he is a full professor at the same institute. His research field is experimental condensed-matter physics, especially involving quantum spin systems and frustrated magnetism.
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