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Zr-based bulk metallic glass clamp cell for high-pressure inelastic neutron scattering
Authors:
S. Hayashida,
T. Wada,
M. Ishikado,
K. Munakata,
K. Iida,
K. Kamazawa,
R. Kajimoto,
Y. Inamura,
M. Nakamura,
K. Iwasa,
K. Ohoyama,
H. Kato,
H. Kira,
M. Matsuura,
Y. Uwatoko
Abstract:
We report the fabrication and characterization of a Zr-based bulk metallic glass (Zr-BMG) clamp cell designed for high-pressure inelastic neutron scattering (INS) measurements. The INS spectra of the empty cell exhibit broad and featureless backgrounds, reflecting the amorphous structure of the Zr-BMG. Test measurements using a reference sample, CsFeCl$_{3}$, confirm that the neutron transmission…
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We report the fabrication and characterization of a Zr-based bulk metallic glass (Zr-BMG) clamp cell designed for high-pressure inelastic neutron scattering (INS) measurements. The INS spectra of the empty cell exhibit broad and featureless backgrounds, reflecting the amorphous structure of the Zr-BMG. Test measurements using a reference sample, CsFeCl$_{3}$, confirm that the neutron transmission of the Zr-BMG cell is significantly higher than that of a conventional monobloc CuBe clamp cell. These results demonstrate that the Zr-BMG clamp cell provides both enhanced neutron transparency and a clean background profile, thereby advancing high-pressure INS studies.
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Submitted 19 April, 2026; v1 submitted 16 February, 2026;
originally announced February 2026.
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Collinear Magnetic Structure in the Diamond Network Magnet EuTi$_2$Al$_{20}$
Authors:
Masahiro Kawamata,
Ryuji Higashinaka,
Takeshi Matsumura,
Maxim Avdeev,
Kazuaki Iwasa,
Hironori Nakao,
Kazumasa Hattori,
Tatsuma D. Matsuda
Abstract:
The magnetic structure of EuTi$_2$Al$_{20}$, in which magnetic Eu$^{2+}$ ions form a diamond network, was investigated using neutron and resonant X-ray diffraction on powder and single-crystal samples. The propagation vector was determined to be $\textbf{\textit{q}}_{\rm m}=(1,0,0)$~r.l.u. from these diffraction measurements. All possible magnetic structures in the space group $Fd\bar{3}m$ with th…
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The magnetic structure of EuTi$_2$Al$_{20}$, in which magnetic Eu$^{2+}$ ions form a diamond network, was investigated using neutron and resonant X-ray diffraction on powder and single-crystal samples. The propagation vector was determined to be $\textbf{\textit{q}}_{\rm m}=(1,0,0)$~r.l.u. from these diffraction measurements. All possible magnetic structures in the space group $Fd\bar{3}m$ with this propagation vector were examined using the irreducible representation method and magnetic space group analysis. This magnetic structure was identified as a collinear antiferromagnetic structure with the magnetic space group $P_Inna$ (\#52.320) or $P_Inn2$ (\#34.164) under zero magnetic field. In these magnetic structure, frustration arises from competing magnetic interactions on the diamond network. These findings provide a concrete experimental reference for assessing the role of competing interactions in diamond-network magnets and motivate further studies of interaction-driven quantum states.
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Submitted 21 February, 2026; v1 submitted 13 January, 2026;
originally announced January 2026.
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Multipole polaron in the devil's staircase of CeSb
Authors:
Y. Arai,
Kenta Kuroda,
T. Nomoto,
Z. H. Tin,
S. Sakuragi,
C. Bareille,
S. Akebi,
K. Kurokawa,
Y. Kinoshita,
W. -L. Zhang,
S. Shin,
M. Tokunaga,
H. Kitazawa,
Y. Haga,
H. S. Suzuki,
S. Miyasaka,
S. Tajima,
K. Iwasa,
R. Arita,
Takeshi Kondo
Abstract:
Rare-earth intermetallic compounds exhibit rich phenomena induced by the interplay between localized $f$ orbitals and conduction electrons. However, since the energy scale of the crystal-electric-field splitting is only a few millielectronvolts, the nature of the mobile electrons accompanied by collective crystal-electric-field excitations has not been unveiled. Here, we examine the low-energy ele…
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Rare-earth intermetallic compounds exhibit rich phenomena induced by the interplay between localized $f$ orbitals and conduction electrons. However, since the energy scale of the crystal-electric-field splitting is only a few millielectronvolts, the nature of the mobile electrons accompanied by collective crystal-electric-field excitations has not been unveiled. Here, we examine the low-energy electronic structures of CeSb through the anomalous magnetostructural transitions below the N$é$el temperature, $\sim$17 K, termed the 'devil's staircase', using laser angle-resolved photoemission, Raman and neutron scattering spectroscopies. We report another type of electron-boson coupling between mobile electrons and quadrupole crystal-electric-field excitations of the 4$f$ orbitals, which renormalizes the Sb 5$p$ band prominently, yielding a kink at a very low energy ($\sim$7 meV). This coupling strength is strong and exhibits anomalous step-like enhancement during the devil's staircase transition, unveiling a new type of quasiparticle, named the 'multipole polaron', comprising a mobile electron dressed with a cloud of the quadrupole crystal-electric-field polarization.
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Submitted 23 February, 2022; v1 submitted 25 May, 2021;
originally announced May 2021.
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Magnetic excitation emergence relevant to carrier scattering in semimetal Yb$_3$Ir$_4$Ge$_{13}$
Authors:
Kazuaki Iwasa,
C. -L. Huang,
Binod K. Rai,
E. Morosan,
Seiko Ohira-Kawamura,
Kenji Nakajima
Abstract:
Inelastic neutron scattering experiments have been conducted to investigate the semimetal system Yb$_3$Ir$_4$Ge$_{13}$. No clear crystal-field-split levels were observed up to an excitation energy of 60 meV, while a magnetic excitation appears at low energy below approximately 3 meV. This excitation shows a short spatial correlation, and an energy spectrum is reproduced by an imaginary part of gen…
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Inelastic neutron scattering experiments have been conducted to investigate the semimetal system Yb$_3$Ir$_4$Ge$_{13}$. No clear crystal-field-split levels were observed up to an excitation energy of 60 meV, while a magnetic excitation appears at low energy below approximately 3 meV. This excitation shows a short spatial correlation, and an energy spectrum is reproduced by an imaginary part of generalized magnetic susceptibility on the basis of a damped harmonic oscillator model. The magnetic excitation emerges simultaneously with an anomalous electrical-resistivity enhancement below 20 K. The close relationship between the magnetic and transport behaviors evidences that the semimetal carriers are scattered by magnetic fluctuation dominated by the Yb $4f$ state.
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Submitted 25 January, 2019; v1 submitted 26 October, 2018;
originally announced October 2018.
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Quantum paramagnet near spin-state transition
Authors:
K. Tomiyasu,
N. Ito,
R. Okazaki,
Y. Takahashi,
M. Onodera,
K. Iwasa,
T. Nojima,
T. Aoyama,
K. Ohgushi,
Y. Ishikawa,
T. Kamiyama,
S. Ohira-Kawamura,
M Kofu,
S. Ishihara
Abstract:
Spin-state transition, also known as spin crossover, plays a key role in diverse systems, including minerals and biological materials. In theory, the boundary range between the low- and high-spin states is expected to enrich the transition and give rise to unusual physical states. However, no compound that realizes a nearly degenerate critical range as the ground state without requiring special ex…
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Spin-state transition, also known as spin crossover, plays a key role in diverse systems, including minerals and biological materials. In theory, the boundary range between the low- and high-spin states is expected to enrich the transition and give rise to unusual physical states. However, no compound that realizes a nearly degenerate critical range as the ground state without requiring special external conditions has yet been experimentally identified. This study reports that, by comprehensive measurements of macroscopic physical properties, X-ray diffractometry, and neutron spectroscopy, the Sc substitution in LaCoO$_3$ destabilizes its nonmagnetic low-spin state and generates an anomalous paramagnetic state accompanied by the enhancement of transport gap and magneto-lattice-expansion as well as the contraction of Co--O distance with the increase of electron site-transfer. These phenomena are not well described by the mixture of conventional low- and high-spin states, but by their quantum superposition occurring on the verge of a spin-state transition. The present study enables us to significantly accelerate the design of new advanced materials without requiring special equipment based on the concept of quantum spin-state criticality.
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Submitted 10 October, 2018; v1 submitted 25 December, 2017;
originally announced December 2017.
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Second-order Structural Transition in Superconductor La$_3$Co$_4$Sn$_{13}$
Authors:
Y. W. Cheung,
J. Z. Zhang,
J. Y. Zhu,
W. C. Yu,
Y. J. Hu,
D. G. Wang,
Yuka Otomo,
Kazuaki Iwasa,
Koji Kaneko,
Masaki Imai,
Hibiki Kanagawa,
Kazuyoshi Yoshimura,
Swee K. Goh
Abstract:
The quasi-skutterudite superconductor La$_3$Co$_4$Sn$_{13}$ undergoes a phase transition at $T^*=152$ K. By measuring the temperature dependence of heat capacity, electrical resistivity, and the superlattice reflection intensity using X-ray, we explore the character of the phase transition at $T^*$. Our lattice dynamic calculations found imaginary phonon frequencies around the ${\bf M}$ point, whe…
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The quasi-skutterudite superconductor La$_3$Co$_4$Sn$_{13}$ undergoes a phase transition at $T^*=152$ K. By measuring the temperature dependence of heat capacity, electrical resistivity, and the superlattice reflection intensity using X-ray, we explore the character of the phase transition at $T^*$. Our lattice dynamic calculations found imaginary phonon frequencies around the ${\bf M}$ point, when the high temperature structure is used in the calculations, indicating that the structure is unstable at the zero temperature limit. The combined experimental and computational results establish that $T^*$ is associated with a second-order structural transition with $\bf{q}$=(0.5, 0.5, 0) (or the ${\bf M}$ point). Further electronic bandstructure calculations reveal Fermi surface sheets with low curvature segments, which allow us to draw qualitative comparison with both Sr$_3$Ir$_4$Sn$_{13}$ and Sr$_3$Rh$_4$Sn$_{13}$ in which similar physics has been discussed recently.
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Submitted 8 June, 2016;
originally announced June 2016.
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Microscopic examinations of Co valences and spin states in electron-doped LaCoO$_{3}$
Authors:
Keisuke Tomiyasu,
Syun-Ichi Koyama,
Masanori Watahiki,
Mika Sato,
Kazuki Nishihara,
Yuki Takahashi,
Mitsugi Onodera,
Kazuaki Iwasa,
Tsutomu Nojima,
Hiroyuki Nojiri,
Jun Okamoto,
Di-Jing Huang,
Yuuichi Yamasaki,
Hironori Nakao,
Youichi Murakami
Abstract:
We studied the Co valences and spin states in electron-doped LaCo$_{1-y}$Te$_{y}$O$_3$ by measuring x-ray absorption spectra and electron spin resonance. The low-temperature insulating state involves the low-spin Co$^{3+}$ ($S=0$) and the high-spin Co$^{2+}$ state, which is described by $g=3.8$ and $j_{\rm eff}=1/2$. The results, in concurrence with the electron-hole asymmetry confirmed in electri…
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We studied the Co valences and spin states in electron-doped LaCo$_{1-y}$Te$_{y}$O$_3$ by measuring x-ray absorption spectra and electron spin resonance. The low-temperature insulating state involves the low-spin Co$^{3+}$ ($S=0$) and the high-spin Co$^{2+}$ state, which is described by $g=3.8$ and $j_{\rm eff}=1/2$. The results, in concurrence with the electron-hole asymmetry confirmed in electrical resistivity, coincide with a spin-blockade phenomenon in this system. Further, we discuss the $g$ factor in terms of the strong covalent-bonding nature and consider multiple origins of this phenomenon.
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Submitted 22 June, 2016; v1 submitted 7 March, 2015;
originally announced March 2015.
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Spin-orbit fluctuations in frustrated heavy-fermion metal LiV$_2$O$_4$
Authors:
K. Tomiyasu,
K. Iwasa,
H. Ueda,
S. Niitaka,
H. Takagi,
S. Ohira-Kawamura,
T. Kikuchi,
K. Nakajima,
K. Yamada
Abstract:
Spin fluctuations were studied over a wide momentum ($\hbar Q$) and energy ($E$) space in the frustrated $d$-electron heavy-fermion metal LiV$_2$O$_4$ by time-of-flight inelastic neutron scattering. We observed the overall $Q$$-$$E$ evolutions near the characteristic $Q=0.6$ Å$^{-1}$ peak and found another weak broad magnetic peak around 2.4 Å$^{-1}$. The data are described by a simple response fu…
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Spin fluctuations were studied over a wide momentum ($\hbar Q$) and energy ($E$) space in the frustrated $d$-electron heavy-fermion metal LiV$_2$O$_4$ by time-of-flight inelastic neutron scattering. We observed the overall $Q$$-$$E$ evolutions near the characteristic $Q=0.6$ Å$^{-1}$ peak and found another weak broad magnetic peak around 2.4 Å$^{-1}$. The data are described by a simple response function, a highly itinerant magnetic form factor, and antiferromagnetic short-range spatial correlations, indicating that heavy-fermion formation is attributable to spin-orbit fluctuations with orbital hybridization.
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Submitted 16 July, 2014;
originally announced July 2014.
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Modified Cross-Correlation for Efficient White-Beam Inelastic Neutron Scattering Spectroscopy
Authors:
K. Tomiyasu,
M. Matsuura,
H. Kimura,
K. Iwasa,
K. Ohoyama,
T. Yokoo,
S. Itoh,
E. Kudoh,
T. Sato,
M. Fujita
Abstract:
We describe a method of white-beam inelastic neutron scattering for improved measurement efficiency. The method consists of matrix inversion and selective extraction. The former is to resolve each incident energy component from the white-beam data, and the latter eliminates contamination by elastic components, which produce strong backgrounds that otherwise obfuscate the inelastic scattering compo…
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We describe a method of white-beam inelastic neutron scattering for improved measurement efficiency. The method consists of matrix inversion and selective extraction. The former is to resolve each incident energy component from the white-beam data, and the latter eliminates contamination by elastic components, which produce strong backgrounds that otherwise obfuscate the inelastic scattering components. In this method, the optimal experimental condition to obtain high efficiency will strongly depend on the specific aim of the individual experiments.
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Submitted 22 March, 2012; v1 submitted 17 November, 2011;
originally announced November 2011.
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Emergence of magnetic long-range order in frustrated pyrochlore Nd$_2$Ir$_2$O$_7$ with metal-insulator transition
Authors:
K. Tomiyasu,
K. Matsuhira,
K. Iwasa,
M. Watahiki,
S. Takagi,
M. Wakeshima,
Y. Hinatsu,
M. Yokoyama,
K. Ohoyama,
K. Yamada
Abstract:
In this study, we performed powder neutron diffraction and inelastic scattering measurements of frustrated pyrochlore Nd$_2$Ir$_2$O$_7$, which exhibits a metal-insulator transition at a temperature $T_{\rm MI}$ of 33 K. The diffraction measurements revealed that the pyrochlore has an antiferromagnetic long-range structure with propagation vector $\vec{q}_{0}$ of (0,0,0) and that it grows with decr…
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In this study, we performed powder neutron diffraction and inelastic scattering measurements of frustrated pyrochlore Nd$_2$Ir$_2$O$_7$, which exhibits a metal-insulator transition at a temperature $T_{\rm MI}$ of 33 K. The diffraction measurements revealed that the pyrochlore has an antiferromagnetic long-range structure with propagation vector $\vec{q}_{0}$ of (0,0,0) and that it grows with decreasing temperature below 15 K. This structure was analyzed to be of the all-in all-out type, consisting of highly anisotropic Nd$^{3+}$ magnetic moments of magnitude $2.3\pm0.4$$μ_{\rm B}$, where $μ_{\rm B}$ is the Bohr magneton. The inelastic scattering measurements revealed that the Kramers ground doublet of Nd$^{3+}$ splits below $T_{\rm MI}$. This suggests the appearance of a static internal magnetic field at the Nd sites, which probably originates from a magnetic order consisting of Ir$^{4+}$ magnetic moments. Here, we discuss a magnetic structure model for the Ir order and the relation of the order to the metal-insulator transition in terms of frustration.
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Submitted 3 January, 2012; v1 submitted 30 October, 2011;
originally announced October 2011.
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Effect of cation size variance on spin and orbital order in Eu$_{1-x}$(La$_{0.254}$Y$_{0.746}$)$_{x}$VO$_3$
Authors:
R. Fukuta,
S. Miyasaka,
K. Hemmi,
S. Tajima,
D. Kawana,
K. Ikeuchi,
Y. Yamasaki,
A. Nakao,
H. Nakao,
Y. Murakami,
K. Iwasa
Abstract:
We have investigated the $R$-ion ($R$ = rare earth or Y) size variance effect on spin/orbital order in Eu$_{1-x}$(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-r…
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We have investigated the $R$-ion ($R$ = rare earth or Y) size variance effect on spin/orbital order in Eu$_{1-x}$(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.
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Submitted 5 October, 2011;
originally announced October 2011.
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Molecular spin-liquid state in spin-3/2 frustrated spinel HgCr$_2$O$_4$
Authors:
K. Tomiyasu,
H. Ueda,
M. Matsuda,
M. Yokoyama,
K. Iwasa,
K. Yamada
Abstract:
A hexamer-type spin excitation seen in spinel chromates $A$Cr$_2$O$_4$ ($A$ = Mg, Zn, or Cd) is the representative spin-liquid-like state caused by geometrical frustration. To clarify an origin of the state, we comparatively studied spin excitations in an isomorphic material HgCr$_2$O$_4$ by inelastic neutron scattering, and observed a different molecular-type excitation. Numerical analyses perfor…
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A hexamer-type spin excitation seen in spinel chromates $A$Cr$_2$O$_4$ ($A$ = Mg, Zn, or Cd) is the representative spin-liquid-like state caused by geometrical frustration. To clarify an origin of the state, we comparatively studied spin excitations in an isomorphic material HgCr$_2$O$_4$ by inelastic neutron scattering, and observed a different molecular-type excitation. Numerical analyses performed using model Hamiltonians suggest that these two types of spin excitations originate from a spin-3/2 molecular singlet hidden in a magnetically ordered phase. The difference between the molecular types is explained by the difference in the kind of exchange interactions occurring in the chromates.
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Submitted 12 April, 2011;
originally announced April 2011.
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Molecular spin-orbit excitations in the J_eff = 1/2 frustrated spinel GeCo$_2$O$_4$
Authors:
K. Tomiyasu,
M. K. Crawford,
D. T. Adroja,
P. Manuel,
A. Tominaga,
S. Hara,
H. Sato,
T. Watanabe,
S. I. Ikeda,
J. W. Lynn,
K. Iwasa,
K. Yamada
Abstract:
We describe powder and single-crystal inelastic neutron scattering experiments on a spinel-type antiferromagnet GeCo$_2$O$_4$, represented by an effective total angular momentum J_eff = 1/2. Several types of non-dispersive short-range magnetic excitations were discovered. The scattering intensity maps in $\vec{Q}$ space are well reproduced by dynamical structure factor analyses using molecular mod…
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We describe powder and single-crystal inelastic neutron scattering experiments on a spinel-type antiferromagnet GeCo$_2$O$_4$, represented by an effective total angular momentum J_eff = 1/2. Several types of non-dispersive short-range magnetic excitations were discovered. The scattering intensity maps in $\vec{Q}$ space are well reproduced by dynamical structure factor analyses using molecular model Hamiltonians. The results of analyses strongly suggest that the molecular excitations below T_N arise from a hidden molecular-singlet ground state, in which ferromagnetic subunits are antiferromagnetically coupled. The quasielastic excitations above T_N are interpreted as its precursor. A combination of frustration and J_eff = 1/2 might induce these quantum phenomena.
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Submitted 21 February, 2011;
originally announced February 2011.
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Spin-orbit coupling inactivity of Co$^{2+}$ ion in geometrically frustrated magnet GeCo$_2$O$_4$
Authors:
Keisuke Tomiyasu,
Ayaka Tominaga,
Shigeo Hara,
Hirohiko Sato,
Tadataka Watanabe,
Shin-Ichi Ikeda,
Kazuaki Iwasa,
Kazuyoshi Yamada
Abstract:
We report single-crystal neutron diffraction studies on a spinel antiferromagnet GeCo$_2$O$_4$, which exhibits magnetic order with a trigonal propagation vector and tetragonal lattice expansion ($c/a\simeq1.001$) below $T_{\rm N}=21$ K. For this inconsistency between spin and lattice in symmetry, magnetic Bragg reflections with a tetragonal propagation vector were discovered below $T_{\rm N}$. We…
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We report single-crystal neutron diffraction studies on a spinel antiferromagnet GeCo$_2$O$_4$, which exhibits magnetic order with a trigonal propagation vector and tetragonal lattice expansion ($c/a\simeq1.001$) below $T_{\rm N}=21$ K. For this inconsistency between spin and lattice in symmetry, magnetic Bragg reflections with a tetragonal propagation vector were discovered below $T_{\rm N}$. We discuss spin and orbital states of Co$^{2+}$ ion underlying the new magnetic component.
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Submitted 4 January, 2011;
originally announced January 2011.
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Detection of Neutron Scattering from Phase IV of Ce0.7La0.3B6: A Confirmation of the Octupole Order
Authors:
K. Kuwahara,
K. Iwasa,
M. Kohgi,
N. Aso,
M. Sera,
F. Iga
Abstract:
We have performed a single crystal neutron scattering experiment on Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically. Below the phase transition temperature 1.5 K of phase IV, weak but distinct superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd number) have been observed by neutron scattering for the first time. The intensity of the superlattic…
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We have performed a single crystal neutron scattering experiment on Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically. Below the phase transition temperature 1.5 K of phase IV, weak but distinct superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd number) have been observed by neutron scattering for the first time. The intensity of the superlattice reflections is stronger for high scattering vectors, which is quite different from the usual magnetic form factor of magnetic dipoles. This result directly evidences that the order parameter of phase IV has a complex magnetization density, consistent with the recent experimental and theoretical prediction in which the order parameter is the magnetic octupoles Tbeta with Gamma5 symmetry of point group Oh. Neutron scattering experiments using short wavelength neutrons, as done in this study, could become a general method to study the high-rank multipoles in f electron systems.
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Submitted 4 August, 2007; v1 submitted 22 June, 2007;
originally announced June 2007.
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Role of p-f Hybridization in the Metal-Non-Metal Transition of PrRu4P12
Authors:
Kazuaki Iwasa,
Lijie Hao,
Tomoo Hasegawa,
Toshiaki Takagi,
Kenji Horiuchi,
Yoshiaki Mori,
Youichi Murakami,
Keitaro Kuwahara,
Masahumi Kohgi,
Hitoshi Sugawara,
Shanta Ranjan Saha,
Yuji Aoki,
Hideyuki Sato
Abstract:
Electronic state evolution in the metal-non-metal transition of PrRu4P12 has been studied by X-ray and polarized neutron diffraction experiments. It has been revealed that, in the low-temperature non-metallic phase, two inequivalent crystal-field (CF) schemes of Pr3+ 4f^2 electrons with Gamma_1 and Gamma_4^(2) ground states are located at Pr1 and Pr2 sites forming the bcc unit cell surrounded by…
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Electronic state evolution in the metal-non-metal transition of PrRu4P12 has been studied by X-ray and polarized neutron diffraction experiments. It has been revealed that, in the low-temperature non-metallic phase, two inequivalent crystal-field (CF) schemes of Pr3+ 4f^2 electrons with Gamma_1 and Gamma_4^(2) ground states are located at Pr1 and Pr2 sites forming the bcc unit cell surrounded by the smaller and larger cubic Ru-ion sublattices, respectively. This modulated electronic state can be explained by the p-f hybridization mechanism taking two intermediate states of 4f^1 and 4f^3. The p-f hybridization effect plays an important role for the electronic energy gain in the metal-non-metal transition originated from the Fermi surface nesting.
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Submitted 5 May, 2005;
originally announced May 2005.
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Evolution of 4f-Electron States in the Metal-Insulator Transition of PrRu$_4$P$_{12}$
Authors:
Kazuaki Iwasa,
Lijie Hao,
Keitaro Kuwahara,
Masahumi Kohgi,
Shanta Ranjan Saha,
Hitoshi Sugawara,
Yuji Aoki,
Hideyuki Sato,
Takashi Tayama,
Toshiro Sakakibara
Abstract:
Magnetic excitations of the filled skutterudite PrRu4P12 exhibiting a metal-insulator (M-I) transition at TM-I= 63 K were studied by inelastic neutron scattering experiment. The spectra at temperatures much lower than TM-I are described as well-defined crystal-field excitations. With approaching TM-I, the excitation peaks broaden and shift considerably together with the temperature variation of…
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Magnetic excitations of the filled skutterudite PrRu4P12 exhibiting a metal-insulator (M-I) transition at TM-I= 63 K were studied by inelastic neutron scattering experiment. The spectra at temperatures much lower than TM-I are described as well-defined crystal-field excitations. With approaching TM-I, the excitation peaks broaden and shift considerably together with the temperature variation of the carrier number and the atomic displacement in the transition. The 4f-electron state evolve from the well localized state in the insulator phase to the strongly hybridized itinerant state by p-f mixing near TM-I. The hybridization is responsible for the M-I transition of PrRu4P12.
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Submitted 5 May, 2005;
originally announced May 2005.
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Direct Observation of Quadrupolar Excitons in the Heavy-Fermion Superconductor PrOs$_{4}$Sb$_{12}$
Authors:
K. Kuwahara,
K. Iwasa,
M. Kohgi,
K. Kaneko,
N. Metoki,
S. Raymond,
M. -A. Measson,
J. Flouquet,
H. Sugawara,
Y. Aoki,
H. Sato
Abstract:
We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOs$_{4}$Sb$_{12}$. The observed excitation clearly softens at a wave vector Q = (1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at Q = (1,0,0) is smaller…
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We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOs$_{4}$Sb$_{12}$. The observed excitation clearly softens at a wave vector Q = (1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at Q = (1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.
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Submitted 7 September, 2005; v1 submitted 27 February, 2005;
originally announced February 2005.