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Y. Motome

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Papers by Y. Motome

Research paper thumbnail of Effects of boson dispersion in fermion-boson coupled systems

Physical Review B, 2000

ABSTRACT

Research paper thumbnail of Geometrical frustration in an elemental solid: An Ising model to explain the defect structure of β-rhombohedral boron

Recently, it was reported that beta -rhombohedral boron has a negative defect formation energy, w... more Recently, it was reported that beta -rhombohedral boron has a negative defect formation energy, which explains the presence of a macroscopic amount (4at.%) of intrinsic defects. In this work, it is shown that the defects in boron have geometrical frustration described by an antiferromagnetic Ising model on an expanded kagome lattice, which is responsible for the reported macroscopic residual entropy.

Research paper thumbnail of Raman-Scattering Measurements and Theory of the Energy-Momentum Spectrum for Underdoped Bi_{2}Sr_{2}CaCuO_{8+δ} Superconductors: Evidence of an s-Wave Structure for the Pseudogap

Physical Review Letters, 2013

We reveal the full energy-momentum structure of the pseudogap of underdoped high-Tc cuprate super... more We reveal the full energy-momentum structure of the pseudogap of underdoped high-Tc cuprate superconductors. Our combined theoretical and experimental analysis explains the spectral-weight suppression observed in the B2g Raman response at finite energies in terms of a pseudogap appearing in the single-electron excitation spectra above the Fermi level in the nodal direction of momentum space. This result suggests an s-wave pseudogap (which never closes in the energy-momentum space), distinct from the d-wave superconducting gap. Recent tunneling and photoemission experiments on underdoped cuprates also find a natural explanation within the s-wave pseudogap scenario.

Research paper thumbnail of Nematic, vector-multipole, and plateau-liquid states in the classical O(3) pyrochlore antiferromagnet with biquadratic interactions in applied magnetic field

Physical Review B, 2010

Nic Shannon 1 , Karlo Penc 2 , and Yukitoshi Motome 3 1 HH Wills Physics Laboratory, University o... more Nic Shannon 1 , Karlo Penc 2 , and Yukitoshi Motome 3 1 HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom 2 Research Institute for Solid State Physics and Optics, PO Box 49, H-1525 Budapest ... R. Moessner and AP Ramirez, Phys. ...

Research paper thumbnail of One- and two-band models for colossal magnetoresistive manganites studied using the truncated polynomial expansion method

Physical Review B, 2006

Considerable progress has been recently made in the theoretical understanding of the colossal mag... more Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance (CMR) effect in manganites. The existence of inhomogeneous states has been shown to be directly related with this phenomenon, both in theoretical ...

Research paper thumbnail of Symmetry considerations on the magnetization process of the Heisenberg model on the pyrochlore lattice

Journal of Physics: Condensed Matter, 2007

Research paper thumbnail of Fluctuation effects by boson dispersion in fermion-boson coupled systems

Research paper thumbnail of Spin, Orbital, Charge and Lattice Coupled Systems-Interplay among Spin, Orbital and Lattice Degrees of Freedom in t2g Electron Systems with Edge-Sharing Network of Octahedra

Research paper thumbnail of Half-Magnetization Plateau in the Pyrochlore Spin-Peierls Model

Research paper thumbnail of A metamagnetic critical point in a three dimensional frustrated antiferromagnet

The competition between different forms of order is central to the problem of strong correlation.... more The competition between different forms of order is central to the problem of strong correlation. This is particularly true of frustrated systems, which frequently exist at or near to a zerotemperature critical point. Here we show that a state with a half-magnetization plateau but no long range order can arise when a three dimensional frustrated antiferromagnet is tuned to a critical point bordering a metamagnetic state. We use classical Monte Carlo simulation and low-temperature expansion techniques to accurately characterize this "spin pseudogap" state, and show how its properties relate to those of the critical point. Our results provide an example of three dimensional spin model which can be used to study the relationship between gap and "pseudogap", -i.e. long range and preformed local order -near a metamagnetic critical point. PACS numbers: 75.10.-b, 75.10.Hk 75.80.+q

Research paper thumbnail of Half-magnetization plateaux in Cr spinels

Journal of Physics: Conference Series, 2006

Magnetization plateaux, visible as anomalies in magnetic susceptibility at low temperatures, are ... more Magnetization plateaux, visible as anomalies in magnetic susceptibility at low temperatures, are one of the hallmarks of frustrated magnetism. An extremely robust halfmagnetization plateau is observed in the spinel oxides CdCr2O4 and HgCr2O4, where it is accompanied by a substantial lattice distortion. We give an overview of the present state experiment for CdCr2O4 and HgCr2O4, and show how such a half-magnetization plateau arises quite naturally in a simple model of these systems, once coupling to the lattice is taken into account.

Research paper thumbnail of Effects of boson dispersion in fermion-boson coupled systems

Physical Review B, 2000

ABSTRACT

Research paper thumbnail of Geometrical frustration in an elemental solid: An Ising model to explain the defect structure of β-rhombohedral boron

Recently, it was reported that beta -rhombohedral boron has a negative defect formation energy, w... more Recently, it was reported that beta -rhombohedral boron has a negative defect formation energy, which explains the presence of a macroscopic amount (4at.%) of intrinsic defects. In this work, it is shown that the defects in boron have geometrical frustration described by an antiferromagnetic Ising model on an expanded kagome lattice, which is responsible for the reported macroscopic residual entropy.

Research paper thumbnail of Raman-Scattering Measurements and Theory of the Energy-Momentum Spectrum for Underdoped Bi_{2}Sr_{2}CaCuO_{8+δ} Superconductors: Evidence of an s-Wave Structure for the Pseudogap

Physical Review Letters, 2013

We reveal the full energy-momentum structure of the pseudogap of underdoped high-Tc cuprate super... more We reveal the full energy-momentum structure of the pseudogap of underdoped high-Tc cuprate superconductors. Our combined theoretical and experimental analysis explains the spectral-weight suppression observed in the B2g Raman response at finite energies in terms of a pseudogap appearing in the single-electron excitation spectra above the Fermi level in the nodal direction of momentum space. This result suggests an s-wave pseudogap (which never closes in the energy-momentum space), distinct from the d-wave superconducting gap. Recent tunneling and photoemission experiments on underdoped cuprates also find a natural explanation within the s-wave pseudogap scenario.

Research paper thumbnail of Nematic, vector-multipole, and plateau-liquid states in the classical O(3) pyrochlore antiferromagnet with biquadratic interactions in applied magnetic field

Physical Review B, 2010

Nic Shannon 1 , Karlo Penc 2 , and Yukitoshi Motome 3 1 HH Wills Physics Laboratory, University o... more Nic Shannon 1 , Karlo Penc 2 , and Yukitoshi Motome 3 1 HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom 2 Research Institute for Solid State Physics and Optics, PO Box 49, H-1525 Budapest ... R. Moessner and AP Ramirez, Phys. ...

Research paper thumbnail of One- and two-band models for colossal magnetoresistive manganites studied using the truncated polynomial expansion method

Physical Review B, 2006

Considerable progress has been recently made in the theoretical understanding of the colossal mag... more Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance (CMR) effect in manganites. The existence of inhomogeneous states has been shown to be directly related with this phenomenon, both in theoretical ...

Research paper thumbnail of Symmetry considerations on the magnetization process of the Heisenberg model on the pyrochlore lattice

Journal of Physics: Condensed Matter, 2007

Research paper thumbnail of Fluctuation effects by boson dispersion in fermion-boson coupled systems

Research paper thumbnail of Spin, Orbital, Charge and Lattice Coupled Systems-Interplay among Spin, Orbital and Lattice Degrees of Freedom in t2g Electron Systems with Edge-Sharing Network of Octahedra

Research paper thumbnail of Half-Magnetization Plateau in the Pyrochlore Spin-Peierls Model

Research paper thumbnail of A metamagnetic critical point in a three dimensional frustrated antiferromagnet

The competition between different forms of order is central to the problem of strong correlation.... more The competition between different forms of order is central to the problem of strong correlation. This is particularly true of frustrated systems, which frequently exist at or near to a zerotemperature critical point. Here we show that a state with a half-magnetization plateau but no long range order can arise when a three dimensional frustrated antiferromagnet is tuned to a critical point bordering a metamagnetic state. We use classical Monte Carlo simulation and low-temperature expansion techniques to accurately characterize this "spin pseudogap" state, and show how its properties relate to those of the critical point. Our results provide an example of three dimensional spin model which can be used to study the relationship between gap and "pseudogap", -i.e. long range and preformed local order -near a metamagnetic critical point. PACS numbers: 75.10.-b, 75.10.Hk 75.80.+q

Research paper thumbnail of Half-magnetization plateaux in Cr spinels

Journal of Physics: Conference Series, 2006

Magnetization plateaux, visible as anomalies in magnetic susceptibility at low temperatures, are ... more Magnetization plateaux, visible as anomalies in magnetic susceptibility at low temperatures, are one of the hallmarks of frustrated magnetism. An extremely robust halfmagnetization plateau is observed in the spinel oxides CdCr2O4 and HgCr2O4, where it is accompanied by a substantial lattice distortion. We give an overview of the present state experiment for CdCr2O4 and HgCr2O4, and show how such a half-magnetization plateau arises quite naturally in a simple model of these systems, once coupling to the lattice is taken into account.

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