Short CV with Selected papers

TOPページ >  members >  Taku J Sato >  Short CV with Selected papers

My Research Experiences, Objectives, and Community Services:

I have worked on the neutron scattering science for more than 25 years using both the reactor- and accelerator-based neutron sources, which include research reactors at JAEA, NIST, ORNL, ANSTO, ILL etc, as well as accelerators such as J-PARC, ISIS and SNS.  Main objectives of my research activity are to elucidate novel many-body states in condensed matters such as heavy fermions, frustrated magnets, and quasicrystals.  I also served as committee member for several scientific societies or institutions, such as International Union of Crystallography (commission member for magnetic structures and Co-Editor for Journal of Applied Crystallography), and Asia-Oceania Neutron Scattering Association (president).

My Technical Skills:

  1. Neutron scattering techniques, including reactor-based triple-axis and SANS techniques, and accelerator-based time-of-flight techniques.
  2. Single crystal growth and their bulk property characterizations, including SQUID magnetometry, x-ray diffraction, and so on.
  3. Analysis skills for neutron inelastic scattering datasets, including linear spin wave analysis, group-theory-based magnetic structure analysis, crystalline electric field splitting analysis and so on.

Selected publications:

  • Ryuji Tamura, Asuka Ishikawa, Shintaro Suzuki, Takahiro Kotajima, Yujiro Tanaka, Takehito Seki, Naoya Shibata, Tsunetomo Yamada, Takenori Fujii, Chin-Wei Wang, Maxim Avdeev, Kazuhiro Nawa, Daisuke Okuyama, Taku J. Sato, Experimental Observation of Long-Range Magnetic Order in Icosahedral Quasicrystals, Journal of the American Chemical Society 143(47) 19938-19944 (2021)

    After 40 years since the discovery of quasicrystals, we finally found one quasicrystal that shows magnetic long-range order!

  • Taku J. Sato, Asuka Ishikawa, Akira Sakurai, Masashi Hattori, Maxim Avdeev, Ryuji Tamura, Whirling spin order in the quasicrystal approximant Au72Al14Tb14, Phys. Rev. B 100(5) 054417-1-6 (2020).

    This work provides the first realistic spin structure model for the complex inter-metallic compound Au72Al14Tb14, also known as “quasicrystal approximate”.  The intriguing “whirling spin order” was confirmed in this materials, providing new interest in this class of materials for the unconventional magnetism as well as transport properties.

  • Okuyama, M. Bleuel, J.S. White, Q. Ye, J. Krzywon, G. Nagy, Z.Q. Im, I. Zivkovic, M. Bartkowiak, H.M. Ronnow, S. Hoshino, J. Iwasaki, N. Nagaosa, A. Kikkawa, Y. Taguchi, Y. Tokura, D. Higashi, J.D. Reim, Y. Nambu, and T.J. Sato, Deformation of the moving magnetic skyrmion lattice in MnSi under electric current flow, Communications Physics 2, 79 (2019).

    I love this work, since this work was made possible by various talents all over the world.  The most important was, of course, a devoted effort of the first author Daisuke Okuyama, as he realize SANS under electric current measurement without thermal gradient.  It was shown experimentally that the magnetic skyrmion lattice a sort of plastic deformation.

  • Nawa, K. Tanaka, N. Kurita, T. J. Sato, H. Sugiyama, H. Uekusa, S. Ohira-Kawamura, K. Nakajima and H. Tanaka, Triplon band splitting and topologically protected edge states in the dimerized antiferromagnet, Nature Communications 10, 2096 (2019).

    Here, we show that the triplon excitation in the coupled dimer compound Ba2CuSi2O6Cl2 has topologically nontrivial character, and indeed can be regarded as a bosonic analogue of topological insulator.  The gap appears at 2.6 meV all over the Brillouin zone, and by a detailed analysis of model spin Hamiltonian it was shown that the surface (much precisely edge) state should form for this compound.

  • Gitgeatpong, Y. Zhao, P. Piyawongwatthana, Y. Qiu, L. W. Harriger, N. P. Butch, T. J. Sato, K. Matan, Nonreciprocal Magnons and Symmetry-Breaking in the Noncentrosymmetric Antiferromagnet, Phys. Rev. Lett., 119, 047201-5 (2017).

    This work was done by my old friend, Prof. Kittiwit Matan.  He had a very strange magnon dispersion (linear crossing at a certain k point) spectrum measured in a-Cu2V2O7 for long time, and we discussed the origin for many years.   Somehow we came up with an idea of classifying the magnon dispersion relation by symmetry, and found that such a linearly crossing dispersion is due to a certain breaking of inversion symmetry.  This is the first-of-the-kind type measurement, which we always try.

  • Taku J. Sato, Daisuke Okuyama, Tao Hong, Akiko Kikkawa, Yasujiro Taguchi, Taka-hisa Arima, Yoshinori Tokura, Magnon dispersion shift in the induced ferromagnetic phase of noncentrosymmetric MnSi, Phys. Rev. B, 84, 144420-1-7 (2016).

    This small piece of work is, I think, one of my best work in recent years.  I can say that this is done by me, myself.  I was (and am) trying to elucidate the symmetry effect to the magnon (and other magnetic quasiparticles), and as a very simple example, I tried to measure ferromagnetic magnon in noncentrosymmetric MnSi.  Experimentally, we needed to realize the inelastic SANS under magnetic field, which was not trivial.  However, thanks to the teach by Dr. Jeff Lynn some 15 years ago, I knew how I should do, and I did it.

  • Hiroki Takahashi, Akira Sugimoto, Yusuke Nambu, Touru Yamauchi, Yasuyuki Hirata, Takateru Kawakami, Maxim Avdeev, Kazuyuki Matsubayashi, Fei Du, Chizuru Kawashima,Hideto Soeda, Satoshi Nakano, Yoshiya Uwatoko, Yutaka Ueda, Taku J. Sato, Kenya Ohgushi, 
Pressure-induced superconductivity in the iron-based ladder material BaFe2S3, Nature Materials 14 (2015) 1008-1012.

    We worked on the Fe-based ladder compounds for a long time, aiming at elucidating how dimensionality changes the superconductivity from 2D Fe-based superconductors.  But, even metallization was not trivial in the beginning.  My contribution for this work is small, only neutron diffraction part, and those who did high-pressure work should have the honor.

  • Matan, T. Ono, Y. Fukumoto, T. J. Sato, J. Yamaura, M. Yano, K. Morita, H. Tanaka, Pinwheel valence-bond solid and triple excitations in the two-dimensional deformed kagome lattice, Nature Physics 6 (2010) 865-9.

    This was also one of specially remembering works.  When we did this kagome work, there was a flood of research activities on Fe superconductors.  We did both, and we published both.  It was a crazily busy time, but certainly we enjoyed it.

  • Matan, R. Morinaga, K. Iida, and T. J. Sato, Itinerant magnetism and spin fluctuations in BaFe2As2: a neutron scattering study, Phys. Rev. B 79 (2009) 054526.

    In this work, we show that spin wave excitation spectrum in the parent compound BaFe2As2 of the Fe-based superconductor using a single crystal sample.  Maybe we need to revisit in future using a better quality single crystal and modern spectrometers, as I still have some interest in the results given in this report, in particular on the itinerant nature.

  • Hiroaki Kadowaki, Naohiro Doi, Yuji Aoki, Yoshikazu Tabata, Taku J. Sato, Jeffrey W. Lynn, Kazuyuki Matsuhira, Zenji Hiroi,
 Observation of Magnetic Monopoles in Spin Ice,
 J. Phys. Soc. Jpn., 78 (2009) 103706-1-4.

    This work was done with my two mentors.  One day in 2008, one of my former advisors called me up and says “let’s observe magnetic monopoles.”  I thought he was gone crazy, but was not.  A theoretical expectation of forming magnetic monopoles in pyrochlore compounds were experimentally confirmed in this work using neutron scattering and simulations.  Although my contribution is not so large (only experimental neutron part), I love this work.

  • M. de Boissieu, S. Francoual, M. Mihalkovic, K. Shibata, A. Q. R. Baron, Y. Sidis, T. Ishimasa, D. Wu, T. Lograsso, L.-P. Regnault, F. Gahler, S. Tsutsui, B. Hennion, P. Bastie, T. J. Sato, H. Takakura, R. Currat and A. P. Tsai,
 Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant, 
Nature Materials 6 (2007) 977-984.

    This is the complete work of atomic excitations in quasicrystal and approximant using both the neutron and x-ray inelastic scattering.   My contribution is small, only a very small part in neutron scattering, but I am very honored to work with the team of quasicrystal expertise.

  • T. J. Sato,
 Short-range order and spin-glass-like freezing in the A-Mg-R (A=Zn or Cd; R = rare-earth elements) magnetic quasicrystals, 
Acta. Crystallogr. Sec. A 61 (2005) 39.

    This is the first review paper summarizing our quasicrystal magnetism research until early 00′.

  • T. J. Sato, S. -H. Lee, T. Katsufuji, M. Masaki, S. Park, J. R. D. Copley, and H. Takagi,
 Unconventional spin fluctuations in the hexagonal antiferromagnet YMnO3,
 Phys. Rev. B 68 (2003) 014432.

    When I was at NIST (2001-2003), I tried to learn things that are new to me.  This is one of them.  We did neutron scattering on the triangular lattice compound YMnO3, and set the interaction parameters, and well as detected spin fluctuations around TN.

  • T. J. Sato, J. W. Lynn and B. Dabrowski,
 Disorder-induced polaron formation in the magnetoresistive perovskite La0.54Ba0.46MnO3,
 Phys. Rev. Lett. 93 (2004) 267204.

    This is also a study made when I was at NIST.   A comparative study on the A-site disordered and ordered perovskites clearly shows different inelastic scattering spectrum.   Through this work, I learned a new way of using triple-axis spectrometer; a small angle inelastic scattering.

  • A. P. Tsai, J. Q. Guo, E. Abe, H. Takakura and T. J. Sato,
 A stable binary quasicrystal,
 Nature 408 (2000) 537.

    This work is…  Needless to say, this is a master piece of work that changed the quasicrystal research field.  The late professor A. P. Tsai, my life-time mentor, did fantastic job in finding quasicrystalline materials, and this is the most impressive one.  Now, the quasicrystal form in “binary” alloy.  But much importantly, this “binary” quasicrystal does not have chemical disorder!

  • T. J. Sato, H. Takakura, A. P. Tsai and K. Shibata,
 Anisotropic spin-correlations in the Zn-Mg-Ho icosahedral quasicrystal,
 Phys. Rev. Lett. 81 (1998) 2364.

    This work is the first study of magnetic correlations in the quasicrystal using the single quasicrystalline sample.  This has two meanings.  The first is the importance of using the single crystal; single quasicrystal generally excludes impurity inclusion, and hence, did give final conclusion of the absence of magnetic long-range order in this magnetic quasicrystal.  Second, the 6D magnetic correlation could be concluded by using the Q scans.