arXiv subjects

Masanori Yamanaka

Publications and source records attributed to Masanori Yamanaka.

At least 19 recordsLinked to original sources

arXiv2026

Lieb-Schultz-Mattis-Type and Laughlin-Type Argument for the Quantum Hall Effect in Lattice Fermions with Spiral Boundary Conditions

We derive the condition for the occurrence of the integer quantum Hall effect in two-dimensional lattice systems with interactions, expressed as $ϕν-ρ\in\mathbb{Z}$, where $ϕ$, $ν$, and $ρ$ denote the magnetic flux, the Chern number, and the electron density, respectively. By employing spiral boundary conditions, which treat the system as an extended one-dimensional chain, this condition is obtained directly through a Lieb-Schultz-Mattis-type and Laughlin-type argument. This approach improves upon the preceding work based on conventional periodic boundary conditions, where the condition was derived indirectly with redundant system-size dependence. The key to this approach is that the spatial directions of the external force and the response can be systematically controlled by a factor of the system size.

cond-mat.str-el↗

arXiv2006

Topologically Linked Crystals

We discovered a new class of topological crystals, namely linked rings of crystals. Two rings of tantalum triselenide (TaSe3) single crystals were linked to each other while crystal growing. The topology of the crystal form is called a "Hopf link", which is the simplest link involving just two component unknots linked together exactly once. The feature of the crystals is not covered by the conventional crystallography.

cond-mat.mtrl-sci↗

arXiv2006

Hofstadter Butterfly Diagram in Noncommutative Space

We study an energy spectrum of electron moving under the constant magnetic field in two dimensional noncommutative space. It take place with the gauge invariant way. The Hofstadter butterfly diagram of the noncommutative space is calculated in terms of the lattice model which is derived by the Bopp's shift for space and by the Peierls substitution for external magnetic field. We also find the fractal structure in new diagram. Although the global features of the new diagram are similar to the diagram of the commutative space, the detail structure is different from it.

hep-th↗

arXiv2005

Quantum wire fracture and discrete-scale invariance

This paper is a study of the behavior of experimentally observed stress-strain force during the fracture of a quantum wire. The magnitude of the force oscillates as a function of time and can be phenomenologically regarded as a sign of discrete-scale invariance. In the theory of discrete-scale invariance, termination of the wire is regarded as a phase transition. We estimate the critical point and exponents.

cond-mat.mes-hall↗

arXiv2005

Physical realization of the four color problem in quantum systems

A multi-component electron model on a lattice is constructed whose ground state exhibits a spontaneous ordering which follows the rule of map-coloring used in the solution of the four color problem. The number of components is determined by the Euler characteristics of a certain surface into which the lattice is embedded. Combining the concept of chromatic polynomials with the Heawood-Ringel-Youngs theorem, we derive an index theorem relating the degeneracy of the ground state with a hidden topology of the lattice. The system exhibits coloring transition and hidden-topological structure transition. The coloring phase exhibits a topological order.

cond-mat.str-el↗

arXiv2005

Extended Hubbard Model with Unconventional Pairing in Two Dimensions

We rigorously prove that an extended Hubbard model with attraction in two dimensions has an unconventional pairing ground state for any electron filling. The anisotropic spin-0 or anisotropic spin-1 pairing symmetry is realized, depending on a phase parameter characterizing the type of local attractive interactions. In both cases the ground state is unique. It is also shown that in a special case, where there are no electron hopping terms, the ground state has Ising-type Néel order at half-filling, when on-site repulsion is furthermore added. Physical applications are mentioned.

cond-mat.str-el↗

arXiv2004

Double-Exchange Model on Triangle Chain

We study ground state properties of the double-exchange model on triangle chain in the classical limit on $t_{2g}$ spins. The ground state is determined by a competition among the kinetic energy of the $e_g$ electron, the antiferromagnetic exchange energy between the $t_{2g}$ spins, and frustration due to a geometric structure of the lattice. The phase diagrams are obtained numerically for two kinds of the models which differ only in the transfer integral being real or complex. The properties of the states are understood from the viewpoint of the spin-induced Peierls instability. The results suggest the existence of a chiral glass phase which is characterized by a local spin chirality and a continuous degeneracy.

cond-mat.str-el↗

arXiv2004

Propagation of Light in Cantor Media

We numerically find that transmission coefficients have a rich structure as a function of wavelength in Cantor media. Complete transmission and complete reflection are observed. We also find that light propagation has scalings with respect to number of layers.

cond-mat.mes-hall↗

arXiv2003

Statistics of Spectra for One-dimensional Quasi-Periodic Systems at the Metal-Insulator Transition

We study spectral statistics of one-dimensional quasi-periodic systems at the metal-insulator transition. Several types of spectral statistics are observed at the critical points, lines, and region. On the critical lines, we find the bandwidth distribution $P_B(w)$ around the origin (in the tail) to have the form of $P_B(w) \sim w^α$ ($P_B(w) \sim e^{-βw^γ}$) ($α, β, γ> 0 $), while in the critical region $P_B(w) \sim w^{-α'}$ ($α' > 0$). We also find the level spacing distribution to follow an inverse power law $P_G(s) \sim s^{- δ}$ ($δ> 0$)

cond-mat↗

arXiv2001

Quantization of Hall Conductance in Double Exchange Systems: Topology and Lattice Gauge Field

We study quantization conditions of the Hall conductivity for a two dimensional system described by a double exchange Hamiltonian with and without an external magnetic field. This is obtained by an extension of the topological arguments familiar from the theory of the integer quantum Hall effect. The quantization conditions are related to spontaneous breaking of spin O(3), time-reversal, and spin chiral symmetries. Extension to systems with higher dimensions is briefly discussed.

cond-mat.mes-hall↗

arXiv2001

Cantor Spectra for Double Exchange Model

We numerically study energy spectra and localization properties of the double exchange model at irrational filling factor. To obtain variational ground state, we use a mumerical technique in momentum space by ``embedded'' boundary condition which has no finite size effect a priori. Although the Hamiltonian has translation invariance, the ground state spontaneously exhibits a self-similarity. Scaling and multi-fractal analysis for the wave functions are performed and the scaling indices $α$'s are obtained. The energy spectrum is found to be a singular continuous, so-called the Cantor set with zero Lebesque measure.

cond-mat.mes-hall↗

arXiv2000

Detecting Gapless Excitations above Ferromagnetic Domain Walls

In a two or three dimensional ferromagnetic XXZ model, a low energy excitation mode above a magnetic domain wall is gapless, whereas all of the usual spin wave excitations moving around the whole crystal are gapful. Although this surprising fact was already proved in a mathematically rigorous manner, the gapless excitations have not yet been detected experimentally. For this issue, we show theoretically that the gapless excitations appear as the dynamical fluctuations of the experimental observable, magnetoresistance, in a ferromagnetic wire. We also discuss other methods (e.g., ferromagnetic resonance and neutron scattering) to detect the gapless excitations experimentally.

cond-mat.mes-hall↗

arXiv2000

Resistance Jumps and Hysteresis in Ferromagnetic Wires

A phenomenological approach based on the principle of minimum heat generation is proposed for understanding experiments for metallic wires with a ferromagnetic domain wall controlled by a magnetic field. This approach elucidates the origin of negative jump and of hysteresis in the magnetoresistance experiments. To justify our approach, we computed the transmission probability of a single electron through a wire. Under certain conditions, the presence of a domain wall enhances the transmission through an impurity potential. Combining this result with the principle of minimum heat generation explains the counterintuitive negative resistance jump.

cond-mat.mes-hall↗

arXiv1998

Scattering of Conduction Electrons by a Ferromagnetic Domain Wall

We study the scattering of an electron by a ferromagnetic domain wall of the quantum Heisenberg-Ising model (XXZ model) with certain boundary conditions. The spin of the electron interacts with the spins of the XXZ model by the Hund coupling. Using the exact domain wall ground states of the XXZ model, we analytically obtain the exact effective Schrödinger equation for conduction electrons. This equation coincides with a conventional phenomenological Schrödinger equation which was derived in a classical treatment of spins of a domain wall. By solving the Schrödinger equation numerically, we have calculated the transmission coefficient which is a function of the Hund coupling and of the anisotropy of the XXZ model. It turns out that the transmission coefficient is vanishing in the low energy limit for the electron.

cond-mat.stat-mech↗

arXiv1998

``Flux'' state in double exchange model

We study the ground state properties of the double-exchange systems. The phase factor of the hopping matrix elements arises from $t_{2g}$ spin texture in two or more dimensions. A novel ``flux'' state is stabilized against the canted antiferromagnetic and spiral spin states. In a certain range of hole doping, the phase separation occurs between the ``flux'' state and antiferromagnetic states. Constructing a trial state which provides the rigorous upper bound on the ground state, we show that the metallic canted antiferromagnetic state is not stable in the double exchange model.

cond-mat.stat-mech↗

arXiv1997

Non-perturbative approach to Luttinger's theorem in one dimension

The Lieb-Schultz-Mattis theorem for spin chains is generalized to a wide range of models of interacting electrons and localized spins in one-dimensional lattice. The existence of a low-energy state is generally proved except for special commensurate fillings where a gap may occur. Moreover, the crystal momentum of the constructed low-energy state is $2k_F$, where $k_F$ is the Fermi momentum of the non-interacting model, corresponding to Luttinger's theorem. For the Kondo lattice model, our result implies that $k_F$ must be calculated by regarding the localized spins as additional electrons.

cond-mat.str-el↗

arXiv1997

Magnetization plateaus in spin chains: ``Haldane gap'' for half-integer spins

We discuss zero-temperature quantum spin chains in a uniform magnetic field, with axial symmetry. For integer or half-integer spin, $S$, the magnetization curve can have plateaus and we argue that the magnetization per site $m$ is topologically quantized as $q (S - m)= integer$ at the plateaus, where $q$ is the period of the groundstate. We also discuss conditions for the presence of the plateau at those quantized values. For $S=3/2$ and $m=1/2$, we study several models and find two distinct types of massive phases at the plateau. One of them is argued to be a ``Haldane gap phase'' for half-integer $S$.

cond-mat.str-el↗

arXiv1996

Correlations in one-dimensional disordered electronic systems with interaction

We investigate the effects of randomness in a strongly correlated electron model in one-dimension at half-filling. The ground state correlation functions are exactly written by products of 3$\times$3 transfer matrices and are evaluated numerically. The correlation lengths depend on randomness when the interaction is effectively weak. On the contrary, they are completely insensitive to randomness when the interaction is effectively strong.

cond-mat.str-el↗