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The High Resolution Chopper Spectrometer (HRC) is installed at the Japan Proton Accelerator Research Complex (J-PARC) and is utilized for a wide range of dynamical studies of materials over a wide energy-momentum space with high resolution. Neutron Brillouin scattering (NBS), i.e., inelastic neutron scattering close to the forward direction, can be performed with the HRC, because this instrument utilizes low angle detectors and high-energy neutrons which facilitates a high resolution. Since the solid angle of the detection area for NBS experiments is limited to very low scattering angles, improvements of the HRC are required to increase the neutron flux with reducing the background. Given the success of the HRC for NBS studies, the neutron intensities for NBS experiments have been improved by changing the detector layout, reducing deformation of the slit package during rotation of the Fermi chopper, and fabricating a longer collimator. At present, we have made further improvements. At around the incident neutron energy Ei = 100 meV, the neutron flux was significantly increased for an energy resolution of ΔE∕Ei = 2%, and the best energy resolution achieved was nearly 1% resolution with an acceptable neutron flux.

Lattice Quantum Chromodynamics (QCD) calculation predicts that a colour-deconfined QCD matter, Quark-Gluon Plasma (QGP), is formed at high temperature and energy density reached in ultra-relativistic heavy-ion collisions. Heavy quarks (charm and beauty) are mostly produced by initial hard scatterings before the formation of the QGP. Therefore heavy-flavour hadrons are ideal probes to investigate the properties of the hot and dense QCD matter. In Pb-Pb collisions, a strong suppression of the production of heavy-flavour hadrons with high transverse momentum has been observed. A deeper understanding of heavy-flavour production and interaction with the QGP requires detailed studies of Cold Nuclear Matter (CNM) effects in order to clarify the role of initial- and final-state effects on their production. CNM effects include shadowing and/or saturation of partons, energy loss in CNM and $k_{\rm{T}}$-broadening. Such effects on heavy quark production can be studied in proton-nucleus collisions via heavy-flavour decays electrons. High-$p_{\rm{T}}$ electrons are especially interesting because they mainly originate from beauty hadrons. We report the $p_{\rm{T}}$ dependence of the nuclear modification factor ($R_{\rm{pPb}}$) and ratio of cross section of heavy-flavour decays electrons in p-Pb collisions with different collision energies, $\sqrt{s_{\mathrm{NN}}} = 8.16\,$TeV and $\sqrt{s_{\mathrm{NN}}} = 5.02\,$TeV., Comment: 4 pages, 6 figures, Proceedings of 8th International Conference on Quarks and Nuclear Physics, Nov. 13-17, 2018

The High Resolution Chopper Spectrometer (HRC) installed at MLF, J-PARC provides opportunities for dynamical studies of materials over a wide energy-momentum space with high resolution. Three types of inelastic neutron scattering experiments can be performed with the HRC: high-resolution experiments in a conventional energy-momentum space, eV neutron spectroscopy, and neutron Brillouin scattering (NBS). Some results have been obtained using these techniques. The NBS option makes the HRC different from other chopper spectrometers. Coherent excitations in non-single-crystal samples can be observed with NBS. On the HRC, NBS experiments were made feasible by reducing the background noise at low scattering angles, and some results were obtained.

Inelastic neutron scattering experiments were performed on an intermetallic compound, MnP. We used a newly developed High Resolution Chopper Spectrometer, HRC, for energy transfers E ≤ 75 meV , besides various triple axis spectrometers; LTAS for energy transfers E ≤ 2 meV , TOPAN for E ≤ 7.5 meV and TAS-1 for E ≤ 35 meV . Spin wave excitations were observed in the ferromagnetic phase of MnP in the entire Brillouin zone along the a⁎- and b⁎-axes. The zone boundary energies of spin waves were determined to be around 60 meV along the a⁎-axis and around 75 meV along the b⁎-axis, and the dispersion relations showed two branches for both axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices.

We installed the data acquisition (DAQ) system on the High Resolution Chopper Spectrometer (HRC) at beamline BL12 at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). In inelastic neutron scattering experiments with the HRC, the event data of the detected neutrons are processed in the DAQ system and visualized in the form of the dynamic structure factor. We confirmed that the data analysis process works well by visualizing excitations in single-crystal magnetic systems probed by inelastic neutron scattering.

To study condensed-matter dynamics over a wide energy–momentum space with high resolution, we constructed the High Resolution Chopper Spectrometer (HRC) at beamline BL12 at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). With the construction nearly completed, we proceeded to characterize the HRC. We confirmed that, under limited conditions, the neutron intensity and energy resolution of the HRC agree well with the design values.

Neutron Brillouin scattering (NBS) experiments can be performed on the High Resolution Chopper Spectrometer (HRC). Recently, an intensity gain of a factor 2.4 with an improved resolution for NBS has been obtained by improving the detector system, the Fermi chopper, and the collimator system. This improved performance provides opportunities for intense studies of dynamics in condensed matter by using non-single-crystal samples.

We developed control and visualization programs, YUI and HANA, for High- Resolution Chopper spectrometer (HRC) installed at BL12 in MLF, J-PARC. YUI is a comprehensive program to control DAQ-middleware, the accessories, and sample environment devices. HANA is a program for the data transformation and visualization of inelastic neutron scattering spectra. In this paper, we describe the basic system structures and unique functions of these programs from the viewpoint of users., 9 pages, 4 figures

The hydrogenation process of aluminum is observed at high pressure and temperature by angle-dispersive in situ X-ray diffraction method. At 10 GPa and 600 °C, single crystals of AlH3 about 20 μm in size are found to grow through three steps: self-pulverization of aluminum, hydrogenation of pulverized aluminum, and solid-state grain growth of hydride. The self-pulverization seems to be the precursor of the hydrogenation reaction because it occurs at pressure temperature conditions where AlH3 is thermodynamically stable.

Shinichi Itoh1, Tetsuya Yokoo1, Takatsugu Masuda2, Hideki Yoshizawa2, Minoru Soda2, Yoichi Ikeda2, Soshi Ibuka1, Daichi Kawana1, Taku J. Sato3, Yusuke Nambu3, Keitaro Kuwahara4, Shin-ichiro Yano5, Jun Akimitsu5, Yoshio Kaneko6, Yoshinori Tokura6,7, Masaki Fujita8, Masashi Hase9, Kazuaki Iwasa10, Haruhiro Hiraka1, Tatsuo Fukuda11, Kazuhiko Ikeuchi12, Koji Yoshida13 Toshio Yamaguchi13, Kanta Ono1, Yasuo Endoh1,6,8 1Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba 305-0801, Japan 2The Institute for Solid State Physics, The University of Tokyo, Tokai 319-1106, Japan 3Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan 4Institute of Applied Beam Science, Ibaraki University, Mito 310-8512, Japan 5Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258, Japan 6RIKEN Center for Emergent Matter of Science, Wako 351-0198, Japan 7Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan 8Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan 9National Institute for Materials Science, Tsukuba 305-0047, Japan 10Department of Physics, Tohoku University, Sendai 980-8578, Japan 11Quantum Beam Science Center, Japan Atomic Energy Agency, Sayo 679-5148, Japan 12Comprehensive Research Organization for Science and Society, Tokai 319-1106, Japan 13Department of Chemistry, Fukuoka University, Fukuoka 814-0180, Japan

The magnetic structures of the low-carrier-system CeP are investigated under magnetic fields up to 12.5 T with the field H ∥[1 \bar1 0] and up to 14 T with H ∥[0 0 1] by synchrotron X-ray diffraction utilizing the unique relationship between the magnetic structure and lattice modulation in this system. The magnetic phases corresponding to the modulation wave vectors k =2/11, 2/10, 2/9 and 2/8 are observed at low temperatures. The magnetic phases with k =2/8 (↑↑°°°°°° or ↑↑←→←→←→), k =2/9 (↑↑°°°°°°° or ↑↑←→←→←→←) and k =2/11 (↑↑°°°°°°°°°) are the new phases under magnetic fields found in the present work. The result demonstrates that magnetic fields play a role similar to high pressure to realize the unique magnetic structure and its multistep change in CeP. This fact indicates the importance of the magnetic polaron effect mediated by the p – f mixing effect in the system.

We have observed superlattice reflections from the low-carrier system CeP under high pressures up to 2 GPa and also under magnetic field up to 12.5 T by means of synchrotron X-ray diffraction. The observed intensities of superlattice reflections are well explained by a model that takes into account both the lattice and charge modulation due to the periodic arrangement of ferromagnetic double layers of Γ8-like Ce ions in the lattice of Γ7 Ce ions. A new magnetic phase with the period of nine Ce planes was found in the experiment at the magnetic field of 12.5 T.

A spin-singlet ground state with a spin gap has been discovered in antiferromagnetic spin chain substances when the spin value is 1/2, 1, or 2. To find spin-gap (singlet-triplet) excitations in spin-$\frac{3}{2}$ chain substances, we performed inelastic neutron scattering and magnetization measurements on $R\mathrm{CrGeO}{}_{5}$ ($R=\text{Y}$ or Sm) powders. As expected, we observed spin-gap excitations and the dispersion relation of the lowest magnetic excitations. We proved that the spin system of $\mathrm{Cr}{}^{3+}$ was an antiferromagnetic alternating spin-$\frac{3}{2}$ chain. We describe the influence of frustration between nearest-neighbor and next-nearest-neighbor exchange interactions in the chain.

Neutron scattering studies were carried out for investigating heavy-electron-like behaviors of PrCu4Au. Excitation spectra are composed of crystal-field (CF) excitations in the Pr3+4f2 electron configuration and a broad component. The CF splitting ground state is a triplet 5. The type-II antiferromagnetic ordering characterized by the propagation vector (1/2, 1/2, 1/2) appears below approximately 4 K. The powder diffraction pattern is reproduced by the ordered magnetic moments aligning along the direction perpendicular to the propagation vector. The magnitude of the ordered magnetic moment is evaluated as 1.36uB/Pr, which is less than 2.0uB/Pr expected from the 5 ground state. Dual electronic states of both localized and itinerant character are inferred.

A new hybrid-type anvil device for high-pressure single-crystal neutron diffraction experiments is described. The device is composed of a large sapphire anvil and a tungsten carbide (WC) anvil which has a hollow in the center of the culet. In a feasibility test of the device, we could generate the pressure up to 5 GPa with high stability. As an example of the application of the hybrid-anvil device, we show some results of magnetic neutron diffraction experiments on filled skutterudite compound PrFe 4 P 12 .

Substitution effect has been studied for the transition metal site on both of the metal–insulator transition in PrRu 4 P 12 and the anomalous nonmagnetic transition (probably of multipolar origin) in PrFe 4 P 12 by mutual alloying. It has been found that both of the transitions are significantly suppressed by the substitution. This observation supports the scenario that the expected Fermi-surface-nesting instability is an essential ingredient for both of the orderings. In the nonordered state, logarithmic temperature dependence in the electrical resistivity indicative of Kondo-like scatterings has been found only around the high Fe concentration, suggesting important roles of the Fe 3d electrons for the strongly correlated behavior.

The filled skutterudite PrFe4P12 undergoes an antiferro-quadrupolar (AFQ) ordering below T Q = 6.5 K . In a recent resistivity measurement under high pressures, it was reported that T Q is suppressed with applied pressure and an insulating phase appears above 2.4 GPa. To obtain microscopic information about the AFQ phase and the insulating state under pressure, we performed X-ray diffraction experiments. We have succeeded in observing superlattice reflections at the wave vector q = ( 1 , 0 , 0 ) with the intensity being ∼ 10 - 4 of the fundamental Bragg's ones. At 1.4 GPa, T Q is suppressed to 5.5 K, while it is found out that the calculated Fe-ion displacement is almost the same as that at ambient pressure. In the insulating state, on the other hand no superlattice reflections at q = ( 1 , 0 , 0 ) are observed within the experimental error.

We performed inelastic neutron scattering experiments on a multiferroic material NdFe3(BO3)4 to explore the crystal field excitations, where the magnetic anisotropy of the Nd3+ crystal field was responsible for the multiferroicity. Flat modes were observed at 8.5 meV and 17.4 meV in the neutron spectrum. The analysis revealed that these excitations were the transitions from the ground state to the first and second excited states of the Nd3+ crystal field.

A quasiperiodic intermediate-valence (IV) system is realized in an icosahedral Au-Al-Yb quasicrystal. X-ray absorption spectroscopy near the Yb ${L}_{3}$ edge indicates that quasiperiodically arranged Yb ions assume a mean valence of 2.61, between a divalent state ($4{f}^{14}$, $J=0$) and a trivalent one ($4{f}^{13}$, $J=7/2$). Magnetization measurements demonstrate that the $4f$ holes in this quasicrystal have a localized character. The magnetic susceptibility shows a Curie-Weiss behavior above $\ensuremath{\sim}100$ K with an effective magnetic moment of 3.81${\ensuremath{\mu}}_{\mathrm{B}}$ per Yb. Moreover, a crystalline approximant to this quasicrystal is an IV compound. We propose a heterogeneous IV model for the quasicrystal, whereas the crystalline approximant is most likely a homogeneous IV system. At temperatures below $\ensuremath{\sim}10$ K, specific heat and magnetization measurements reveal non-Fermi-liquid behavior in both the quasicrystal and its crystalline approximant without either doping, pressure, or field tuning.

We have investigated the $R$-ion ($R$ $=$ rare earth or Y) size variance effect on spin/orbital order in Eu${}_{1\ensuremath{-}x}$(La${}_{0.254}$Y${}_{0.746}$)${}_{x}$VO${}_{3}$. The size variance disturbs one-dimensional orbital correlation in $C$-type spin/$G$-type orbital ordered states and suppresses this spin/orbital order. In contrast, it stabilizes the other spin/orbital order. The results of neutron and resonant x-ray scattering denote that in the other ordered phase, the spin/orbital patterns are $G$ type/$C$ type, respectively.

Structural change of lanthanum dihydride LaH${}_{2.3}$, which has a face-centered-cubic (fcc) metal lattice with tetrahedral interstitial sites fully occupied with hydrogen atoms and partially occupied octahedral sites, has been investigated at high pressures up to 20 GPa at ambient temperature by synchrotron radiation x-ray diffraction. Additional Bragg reflections appear just on higher angle sides of the original ones at $~11$ GPa and their peak intensities increase gradually on further compression. The coexistence state of two fcc metal lattices thus observed above 11 GPa is interpreted in terms of phase separation or disproportionation reaction from the dihydride toward a solid solution and trihydride states, in both of which the octahedral interstitial sites are partially occupied with hydrogen atoms. A gradual distortion from the cubic to a tetragonal lattice is observed prior to the phase separation. The coexistence phase goes back to the dihydride fcc phase via the lattice distorted phase with decreasing pressure.

A quasiperiodic intermediate-valence system was prepared by applying pressure to an icosahedral Cd-Yb quasicrystal. In this system, each quasiperiodic lattice point has a charge degree of freedom. $\text{Yb}\text{ }{L}_{\text{III}}$ x-ray absorption spectroscopy experiments demonstrate that the Yb valence increases continuously upon compression from a divalent state at ambient pressure and reaches 2.33 at 31.7 GPa. A comparison study to the crystalline approximant suggests that the quasiperiodically arranged Yb ions have a homogeneous intermediate valence that takes a valence fluctuation state under pressure.

Structural change of LaH2 has been investigated at high pressure and low temperature by synchrotron radiation X-ray diffraction. LaH2 has an fcc metal lattice with interstitial hydrogen atoms located at tetrahedral sites. The fcc-LaH2 decomposes into two phases, which have different hydrogen compositions such as hydrogen-poor LaH and hydrogen -rich LaH2+δ phases, at 11 GPa at room temperature. In spite of largely suppressed diffusivity of the interstitial hydrogen atoms at low temperature, we have found the disproportionation reaction around 14 GPa at 200 K. Difference in the molar volume between each phases suggests monohydride LaH is formed as the disproportionation product even at low temperature. The volume fraction of the hydrogen-poor phase relative to the hydrogen-rich one at 200 K rapidly rises against pressure and reaches to ~0.45 at ~17 GPa.

We improved the High Resolution Chopper Spectrometer (HRC), which is installed at MLF in J-PARC, in order to perform neutron Brillouin scattering (NBS) experiments, and successfully demonstrated a feasibility of this method. Gapless spin-wave excitations were observed in La0.8Sr0.2MnO3, which were in good agreement with previous results using single crystals, on the other hand, a large energy gap in the ferromagnetic spin waves was found in SrRuO3. Spin-wave peaks in a permanent magnet Nd2Fe14B were on the dispersion curve determined previously using a single crystal. Excitations, so-called fast sound, in liquid D2O were in a good agreement with previous inelastic neutron scattering experiments and the dispersion curve were extended to the lower Q region.

Quantum spins in one-dimensional (1D) chains exhibit characteristic features such as the Haldane gap (S=1) and the spin-Peierls state (S=1/2). Recently multi degrees of freedom in cooperation with quantum spins are focused. We present here spin dynamics in the lightly hole doped Nd2-xCaxBaNiO5 (x=0.035), 1D Haldane system by means of pulsed neutron inelastic scattering method. One-magnon band with a spin gap (Haldane gap) was visible with the decrease of the zone boundary energy to 60 meV. In contrast, the spin gap slightly increases. Dynamical structures inside spin gap upon carrier doping showing incommensurate structure centered at the magnetic zone center was newly observed which is possibly originating from the doped holes in Haldane chains.

Inelastic neutron scattering experiments on an intermetallic compound, MnP, were performed by using a chopper spectrometer as well as triple axis spectrometers. Spin waves were observed in the ferromagnetic phase in the entire Brillouin zone along the a*- and b*-axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices.

The neutron Brillouin scattering (NBS) method, which was developed using advanced neutron sources, was extended to an intense pulsed spallation neutron source. The feasibility of this method was demonstrated by observing ferromagnetic spin waves in La0.8Sr0.2MnO3 and SrRuO3 powders. Gapless spin-wave excitations were observed in La0.8Sr0.2MnO3, which were continuously extrapolated to the lower scattering vector \(Q\) from previous results using single crystals. The novel result is a well-defined quadratic \(Q\) dependence in the spin-wave dispersion curve with a large energy gap in SrRuO3.

A new high-pressure apparatus for magnetic neutron diffraction studies are described. Maximum pressure generated by the anvil-type high-pressure cell with 2.5 mm anvil tip and Cu–0.3% P gasket is about 6 GPa at present. The neutron-focusing device with many supermirrors, which is useful for the experiments with tiny sample, is also shown.

Magnetic structures of CeP have been studied under high magnetic fields up to 12.5 T (H|| [1 1 0]) by synchrotron X-ray diffraction. Magnetic phases with wave vectors k= 2 11 , 2 10 and 2 9 were observed at low temperatures. The magnetic phases with k= 2 9 (↑↑∘∘∘∘∘∘∘ or ↑↑←→←→←→←) and k= 2 11 (↑↑∘∘∘∘∘∘∘∘∘) are new phases under magnetic field found in the present work.

The High Resolution Chopper Spectrometer (HRC) was installed at J-PARC, to study dynamics in condensed matters with high-resolutions and relatively-high-energy neutrons. Although the HRC was damaged by the earthquake disaster, we recovered and started neutron scattering experiments. During the recovery works, we also improved the performance of the HRC, by installing a supermirror guide tube, a collimator system, an experiment control environment etc.

The neutron Brillouin scattering (NBS) method was employed at the High Resolution Chopper Spectrometer (HRC) installed at J-PARC. With the recent developments in pulsed neutron sources that can realize high-energy incoming neutrons, the NBS method can be explored to facilitate further developments in material science. As a typical example, ferromagnetic spin waves in a polycrystalline sample of La0.8Sr0.2MnO3 were measured. Spin waves with a Q2 dispersion relation were clearly observed, which agreed well with previous studies that used single crystals.

We performed inelastic neutron scattering experiments on a three-dimensional magnetic system MnP, which is a ferromagnetic inter-metallic compound below TC = 291 K and transitions into a screw state at T* = 47 K. Using newly developed high resolution chopper spectrometer (HRC) and triple axis spectrometer LTAS (for E = 0?2 meV), 6G (for E = 2?8 meV) TAS1 (for E = 10-35 meV), we succeeded in observing the excitations from low energy to Brillouin zone center. We assumed isotropic 6 exchange parameters, and calculated dispersion relation using Heisenberg model for 2-sub lattices. We confirm that nearest neighbor (n.n) exchange parameters Jm are J > 0 (ferromagnetic interaction), the next nearest neighbor (n.n.n) exchange parameters are J < 0 (anti-ferromagnetic interaction), We conclude that the competition between n.n and n.n.n would be the cause of helimagnetic structure in MnP.

The dispersion relations of the lowest magnetic excitations at low temperatures and the temperature dependence of the inverse magnetic correlation length were determined using inelastic pulsed neutron scattering experiments on the following one-dimensional Heisenberg antiferromagnets: CsVCl 3 ( S = 3/2), CsVBr 3 ( S = 3/2), CsCrCl 3 ( S = 2), and CsNiCl 3 ( S = 1). From studying the exchange constant, J , it has been found that the observed energies of the magnetic excitations require a quantum renormalization factor that is dependent on the spin quantum number, S . The values of J were determined from the temperature dependence of the inverse magnetic correlation length, which describes the static correlation function that can be deduced from the energy-integrated dynamical structure factor. We demonstrated that the S -dependent quantum renormalization effect was detected by only inelastic pulsed neutron scattering experiments, and that the effect was consistent with quantum Monte Carlo calculations.

A quasiperiodic intermediate-valence system is demonstrated by applying pressure to an icosahedral Cd–Mg–Yb quasicrystal as well as our previous report on a Cd–Yb quasicrystal [Phys. Rev. B 81 (2010) 220202(R)]. Yb L III -edge x-ray absorption spectroscopy experiments demonstrate that the Yb valence increases continuously upon compression from the divalent state at ambient pressure, and reaches a valence of 2.37 at 16.3 GPa. Unlike other known quasicrystals, these Yb-based quasiperiodic intermediate-valence systems have the following two characteristics. 1) Each quasiperiodic lattice point has a charge degree of freedom, and 2) pressure can control the strength of the electron correlations.

The order parameter in the pressure-induced insulating phase of the filled skutterudite compound PrFe 4 P 12 has been investigated using a high-pressure single-crystal neutron diffraction technique. Clear evidence of the antiferromagnetic order with the propagation vector q = (1, 0, 0) was observed in the insulating phase above 2.7 GPa. The q = (1, 0, 0) structure is identical with that in the nonmagnetic ordered phase below 2.5 GPa and with the nesting property of the Fermi surface. The observed magnetic moment of the Pr ion is 2 µ B and almost pressure-independent up to at least 4.2 GPa. The 2 µ B magnetic moment originates from the dipole in the low-lying quasi-quartet crystal field state. The pressure-induced antiferromagnetic structure at 3.2 GPa is suppressed by applying a magnetic field of about 1.5 T, which is interpreted as a flop of magnetic moments into the alignment of the ferromagnetic state. This brings about a steep decrease in the electrical resistivity due to the disappearance of the anti...

We report the first X-ray diffraction experiments of PrFe 4 P 12 under high pressure. We discovered a symmetry lowering from cubic to orthorhombic or lower at the metal–insulator transition temperature, accompanied by a jump in the lattice constant, which indicates a first-order phase transition. The superlattice reflections at q =(1,0,0) observed in the low-pressure nonmagnetic ordered phase are found to disappear in the insulating phase. The temperature dependence of the lattice constant and the absence of the superlattice reflections are well explained by taking into account an antiferromagnetic ordering.

Inelastic neutron scattering experiment is performed on single crystals of multiferroics NdFe 3 ( 11 BO 3 ) 4 to explore the magnetic excitations. Fe-centered dispersive excitation with the band width of 5 meV is observed along the crystallographic c ∗ direction and that of 3 meV is along the a ∗ direction. The energy gap of 0.57 meV due to an axial-type anisotropy is ob- served at the AF zone center. The energy of Nd-centered flat excitation is 1 meV. Furthermore, anticrossing of the Fe- and Nd-centered excitations is observed, meaning the existence of the f - d coupling, i.e., the interaction between the Nd 3+ and Fe 3+ moments. Spin-wave analysis on the observed neutron spectrum revealed the underlying magnetic Hamiltonian in NdFe 3 ( 11 BO 3 ) 4 . Discussion on the axial-type anisotropy in the ab - plane based on the magnetic model leads to the conclusion that the anisotropy of the Nd 3+ ion plays a main role in the determination of the structures of both magnetic moment and electric polarization in NdFe 3 (BO 3 ) 4 .