承認日 Date of Approval 2017/6/28
承認者 Approver Ryoichi Kajimoto
提出日 Date of Report 2017/6/28

Experimental Report

Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
Name of sample(s) and chemical formula, or compositions including physical form.
Polycrystalline Li2ScMo3O8.

Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

New molecular-based triangular lattice magnets Li 2AMo3O8 (A = In or Sc) were recentlysynthesized. Mo3O13 cluster in Li2AMo3O8 has one unpaired spin, and Mo3O13 clusters form a perfect
triangular lattice. Bulk and NMR measurements reported that the ground states of Li 2InMo3O8 andLi2ScMo3O8 are 120° long-range magnetic ordered state and the quantum spin liquid, respectively.
Since the ground state of the spin-1/2 perfect triangular lattice with antiferromagnetic nearest neighborinteractions is so-called 120° long range order, to understand the origin of the unexpected QSL state inLi2ScMo3O8 is important. However, no inelastic neutron scattering measurement has been reported on
the exotic QSL state in Li2ScMo3O8 nor on the long-range ordered state in isostructural Li 2InMo3O8. In
this experiment, we performed inelastic neutron scattering measurements on Li 2AMo3O8 (A = Sc andIn) using the Fermi chopper spectrometer 4SEASONS to discuss the nature of the QSL state in
Li2ScMo3O8 and mechanism of the different ground states between the Sc and In systems.
We performed inelastic neutron scattering measurements on Li 2ScMo3O8 at 1.7, 5.0, 15, and 40 K.
The Fermi chopper was rotated in 250 Hz, resulting in the multi-Ei of 23.9, 15.0, 10.3, and 7.5 meV. The
Experimental method and results (continued)1polycrystalline sample was packed into the aluminum sample. Effective sample thickness was 1 mm.
We also measured the empty can at 1.7 and 40 K.
Figure 1(a) shows the neutron scattering intensity map from Li 2ScMo3O8 at 1.7 K with Ei = 23.9
meV. At very low Q (Q < 0.8-1), there is a continuum magnetic excitation, which is the signature ofthe QSL. To see this magnetic excitation in detail, we cut the map alongand Q. Figures 1(b) and1(c) are the energy and Q dependences of the neutron scattering intensities, respectively. The
signature of the magnetic excitations from QSL was observed.
In the preliminary measurements, we also measured the magnetic long range ordered state of
Li2InMo3O8. Figure 1(d) shows the neutron scattering intensity map from Li 2InMo3O8 at 4 K. Clearly,
spin wave excitation evolves from (1/3, 1/3, 0) corresponding to the 120° long range order. Linear spinwave calculation succeeded in reproducing the excitation spectrum as shown in Fig. 1(e).
As shown in Figs. 1(a) and 1(d), Li2ScMo3O8 and Li2InMo3O8 shows completely different magneticexcitations, representing the different ground states. We are now trying to understand the origin of theQSL in Li2ScMo3O8 by analyzing the magnetic excitations.
Finally, we appreciate very much the MLF SE team for their professional support.

Figure 1 (a) Neutron scattering intensity map from Li2ScMo3O8 at 1.7 K with Ei = 23.9 meV. (b) Energy(Q = [0.6, 0.9]-1) and (c) Q dependences (= [4.5, 6] meV) of Li2ScMo3O8 at 1.7 K. (d) Neutron

scattering intensity map from Li2InMo3O8 at 4 K with Ei = 11.9 meV. (e) Linear spin wave calculation forLi2InMo3O8 at 4 K assuming the energy resolution of Ei = 11.9 meV and 350 Hz.

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