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Nawa, Kazuhiro*; Tanaka, Kimihito*; Kurita, Nubuyuki*; Sato, Taku*; Sugiyama, Haruki*; Uekusa, Hidehiro*; Kawamura, Seiko; Nakajima, Kenji; Tanaka, Hidekazu*
Nature Communications (Internet), 10, p.2096_1 - 2096_8, 2019/05
Times Cited Count:16 Percentile:74.1(Multidisciplinary Sciences)Search for topological materials has been actively promoted in the field of condensed matter physics for their potential application in energy-efficient information transmission and processing. Recent studies have revealed that topologically invariant states, such as edge states in topological insulators, can emerge not only in a fermionic electron system but also in a bosonic system, enabling nondissipative propagation of quasiparticles. Here we report the topologically nontrivial triplon bands measured by inelastic neutron scattering on the spin-1/2 two-dimensional dimerized antiferromagnet BaCuSiOCl. The excitation spectrum exhibits two triplon bands that are clearly separated by a band gap due to a small alternation in interdimer exchange interaction, consistent with a refined crystal structure. By analytically modeling the triplon dispersion, we show that BaCuSiOCl is the first bosonic realization of the coupled Su-Schrieffer-Heeger model, where the presence of topologically protected edge states is prompted by a bipartite nature of the lattice.
Harada, Masahide; Yamaguchi, Yuji; Kawamura, Seiko; Kofu, Maiko; Nirei, Masami; Haga, Katsuhiro; Oku, Takayuki; Matsuura, Masato*; Kusaka, Katsuhiro*; Nakayama, Haruki*
no journal, ,
In the Materials and Life science experimental Facility (MLF) at J-PARC, 3 GeV proton beam is injected into a mercury target to provide neutrons produced by spallation reactions to neutron instruments, and as of June 2023, MLF is operating at 800 kW proton beam output. The intensity of neutrons provided to the neutron instruments is an important factor to characterize the performance of the neutron instruments. So far, neutron intensity measurements have been done with He-3 counters and gold foil activation methods. To measure both spatial distribution and absolute value simultaneously with high accuracy was an issue. To solve this issue, we proposed the large-area gold-foil activation method for thermal neutrons. In this presentation, we will explain the method of the large-area gold foil activation method and report examples of its application to neutron intensity and distribution measurements at BL02, BL03, and BL14.