arXiv subjects

Chisa Hotta

Publications and source records attributed to Chisa Hotta.

62 records · Page 4Linked to original sources

arXiv2009

Non-local network-excitation in the Ising antiferromagnet on the anisotropic triangular lattice

We study the Ising antiferromagnet on the triangular lattice which are interacting along three different directions via two $J$-bonds and one anisotropic $J'$-bond with $J' \ge J$. Although its finite temperature state has long been considered as simply disordered, we find a systematic generation of a ferromagnetic $J'$-bonds named "good defects" each carrying the energy $2δ_J\equiv 2(J'-J)$. They exhibit an eminent correlation which is regarded as a network or a soft lattice. The specific heat shows a universal peak at $T^* \sim δ_J$ and the corresponding energy follows the activation type of temperature-dependence with an excitation gap $2δ_J$. Energetics and the crossover between this particular two-dimensional state and the other disordered or one-dimensional states are discussed.

cond-mat.str-el↗

arXiv2008

Dimensional tuning of electronic states under strong and frustrated interactions

We study a model of strongly interacting spinless fermions on an anisotropic triangular lattice. At half-filling and the limit of strong repulsive nearest-neighbor interactions, the fermions align in stripes and form an insulating state. When a particle is doped, it either follows a one-dimensional free motion along the stripes or fractionalizes perpendicular to the stripes. The two propagations yield a dimensional tuning of the electronic state. We study the stability of this phase and derive an effective model to describe the low-energy excitations. Spectral functions are presented which can be used to experimentally detect signatures of the charge excitations.

cond-mat.str-el↗

arXiv2007

Universal temperature dependence of the magnetization of gapped spin chains

Temperature dependence of the magnetization of the Haldane spin chain at finite magnetic field is analyzed systematically. Quantum Monte Carlo data indicates a clear minimum of magnetization as a function of temperature in the gapless regime. On the basis of the Tomonaga-Luttinger liquid theory, we argue that this minimum is rather universal and can be observed for general axially symmetric quasi-one-dimensional spin systems. Our argument is confirmed by the magnetic-field dependence of the spin-wave velocity obtained numerically. One can estimate a magnitude of the gap of any such systems by fitting the experimental data with the magnetization minimum.

cond-mat.str-el↗

arXiv2006

Phase Diagram of Spinless Fermions on an Anisotropic Triangular Lattice at Half-filling

The strong coupling phase diagram of the spinless fermions on the anisotropic triangular lattice at half-filling is presented. The geometry of inter-site Coulomb interactions rules the phase diagram. Unconventional charge ordered phases are detected which are the recently reported pinball liquid and the striped chains. Both are induced by the quantum dynamics out of classical disordered states and afford extremely correlated metallic states and the particular domain wall-type of excitations, respectively. The disorder once killed by the quantum effect revives at the finite temperature, which is discussed in the terms of the organic $θ$-ET$_2X$.

cond-mat.str-el↗

arXiv2006

Filling dependence of a new type of charge ordered liquid on a triangular lattice system

We study the recently reported characteristic gapless charge ordered state in a spinless fermion system on a triangular lattice under strong inter-site Coulomb interactions. In this state the charges are spontaneously divided into solid and liquid component, and the former solid part aligns in a Wigner crystal manner while the latter moves among them like a pinball. We show that such charge ordered liquid is stable over a wide range of filling, $1/3<n<2/3$, and examine its filling dependent nature.

cond-mat.str-el↗

arXiv2006

Strong coupling theory of the spinless charges on the triangular lattices: possibility of a new quantum liquid

We propose a new type of charge liquid state in the spinless fermion system on a triangular lattice under strong inter-site Coulomb interactions, $V$. In the strong coupling limit ($t=0$), the ground state is classical and disordered due to geometrical frustration. The introduction of small t will drive the system to a partially ordered phase which we call a "pinball liquid". A possibly long range ordered Wigner crystal solid coexist with a liquid component which are moving around them like a pinball. This liquid is dominant over wide range of filling, even away from the regular triangle, and is also realized in the hard core boson systems. Relevance to the organic theta-ET_2X is discsussed.

cond-mat.str-el↗

arXiv2005

New possibility of the ground state of quarter-filled one-dimensional strongly correlated electronic system interacting with localized spins

We study numerically the ground state properties of the one-dimensional quarter-filled strongly correlated electronic system interacting antiferromagnetically with localized $S=1/2$ spins. It is shown that the charge-ordered state is significantly stabilized by the introduction of relatively small coupling with the localized spins. When the coupling becomes large the spin and charge degrees of freedom behave quite independently and the ferromagnetism is realized. Moreover, the coexistence of ferromagnetism with charge order is seen under strong electronic interaction. Our results suggest that such charge order can be easily controlled by the magnetic field, which possibly give rise to the giant negative magnetoresistance, and its relation to phthalocyanine compounds is discussed.

cond-mat.str-el↗

arXiv2005

Comments on "Dimerization Induced by the RKKY Interaction"

Recently, Xavier et al. claimed the existence of an insulating spin dimer state in the one-dimensional Kondo lattice model at quarter-filling amidst the paramagnetic metallic phase. In this comment we show that the dimer-dimer correlation decays algebraically at long distances and the charge gap vanishes in the bulk limit.

cond-mat.str-el↗