Searcharxiv⌕ Search

arXiv subjects

Takao Suzuki

Publications and source records attributed to Takao Suzuki.

35 records · Page 2Linked to original sources
arXiv2010

A Particular Solution of a Painlevé System in Terms of the Hypergeometric Function ${}_{n+1}F_n$

In a recent work, we proposed the coupled Painlevé VI system with $A^{(1)}_{2n+1}$-symmetry, which is a higher order generalization of the sixth Painlevé equation ($P_{\rm VI}$). In this article, we present its particular solution expressed in terms of the hypergeometric function ${}_{n+1}F_n$. We also discuss a degeneration structure of the Painlevé system derived from the confluence of ${}_{n+1}F_n$.

math-ph↗
arXiv2010

Change of the Ground State upon Hole Doping Unveiled by Ni Impurity in High-$T_{\rm c}$ Cuprates

The electronic ground state in high-$T_{\rm c}$ cuprates where the superconducting state is suppressed by Ni substitution has been investigated in La$_{2-x}$Sr$_x$Cu$_{1-y}$Ni$_y$O$_4$ from the specific heat and muon spin relaxation measurements. It has been found that the ground state changes from a magnetically ordered state with the strong hole-trapping by Ni to a metallic state with the Kondo effect of Ni with increasing hole-concentration. Moreover, the analysis of the results has revealed that a phase separation into the magnetically ordered phase and the metallic phase occurs around the boundary of two phases.

cond-mat.supr-con↗
arXiv2010

Pressure-induced new magnetic phase in Tl(Cu$_{0.985}$Mg$_{0.015}$)Cl$_3$ probed by muon spin rotation

We carried out zero-field muon-spin-rotation (ZF-$μ$SR) measurements in hydrostatic pressures in impurity-doped quantum spin gap system Tl(Cu$_{0.985}$Mg$_{0.015}$)Cl$_3$ to investigate microscopic magnetic properties of the pressure-induced phase. The spontaneous muon spin precession, which indicates the existence of a long-range coherent order, is observed in pressures. With decreasing temperature in 3.1 kbar, the internal static magnetic field at the muon sites {\it H}$_{\rm int}$ tends to saturate to 280 Oe around 4 K, however, decreases to 240 Oe at 2.3 K. These results suggest a rearrangement of ordered spins, and we speculate that the oblique antiferromagnetic phase, which is observed in the pressure of 14 kbar on the pure TlCuCl$_3$, appears in the Mg-doped system in lower pressures.

cond-mat.str-el↗
arXiv2008

Pressure-Induced Reentrant Oblique Antiferromagnetic Phase in Spin Dimer System TlCuCl_3

Magnetization measurements under a hydrostatic pressure of P = 1.4 GPa were performed on the coupled spin dimer system TlCuCl_3, which exhibits a pressure-induced quantum phase transition from a gapped singlet state to an antiferromagnetic state at P_c = 0.042 GPa. Antiferromagnetic ordering with ordered moments parallel to the ac plane was observed at T_N = 16.7 K at 1.4 GPa. The spin reorientation phase transition was observed at T_R ~ 9.2 K for zero magnetic field, at which the ordered moments start to incline towards the b axis. With increasing external field parallel to th b axis, a second-order phase transition from the oblique antiferromagnetic (OAF) phase to the spin-flop (SF) phase occurs below T_R. We argue that the OAF phase arises from the competition between the anisotropic energies of the conventional second order and the fourth order, that increases with increasing pressure. We discuss the OAF-SF transition within the framework of the mean field approximation.

cond-mat.str-el↗
arXiv2008

μSR-detection of the soft-mode toward the exotic magnetic ground state in bond-disordered quantum spin system IPA-Cu(Cl$_{0.35}$Br$_{0.65}$)$_3$

The spin-gap system with a bond-disorder (CH3)2CHNH3-Cu(ClxBr1-x)3 is reported by experiments on macroscopic quantities of the uniform susceptibility and the specific heat to show a magnetic order at low temperatures when the value of x is within the limited region between 0.44 and 0.87, and otherwise a gapped behavior. We have investigated microscopically the ground state of the sample with x=0.35 by muon spin relaxation (mSR) to observe that the frequency spectrum of the spin fluctuation tends to concentrate around zero energy as lowering temperatures. This behavior was interpreted as the soft-mode toward the possible magnetic phase transition at absolute zero.

cond-mat.str-el↗
arXiv2007

High-field Magnetic Torque Measurements in (CH$_3$)$_2$CHNH$_3$CuCl$_3$

High-field magnetic torque measurements were carried out in the spin gap system (CH$_3$)$_2$CHNH$_3$CuCl$_3$. It was observed that the magnitude of the magnetic torque $τ$ is almost zero until the critical field and then increases rapidly, which indicates the existence of the magnetic quantum phase transition from the spin-gap phase to the field-induced magnetic ordered phase. From the temperature dependence of the magnetic torque $τ$, the cusp-like minimum indicative of the Bose-Einstein condensation (BEC) of magnons was observed for $H \perp$ C-plane, while the kink-anomaly was observed for $H \perp$ A-plane at the field-induced transition temperature. It was found that this different behavior between $H \perp$ A-plane and $H \perp$ C-plane can be interpreted as the breaking of the magnon BEC picture due to the rotational symmetry breaking. The additional anomaly was also observed in the field-induced magnetic ordered phase at the intermediate angle of the applied magnetic field in the A-plane and discussed in terms of the spin-flop transition, the spin-reorientation transition and the spin-lattice correlations. In order to investigate the spin-lattice correlations in (CH$_3$)$_2$CHNH$_3$CuCl$_3$, we performed the magnetostriction measurements and observed that the magnetostriction appears by vanishing of the spin gap.

cond-mat.str-el↗
arXiv2007

The effect of randomness on the quantum spin system Tl$_{1-x}$K$_x$CuCl$_3$ with ${\boldmath $x$}$ = 0.44 studied by the Zero-field Muon-Spin-Relaxation (ZF-$μ$SR) method

Zero-field muon-spin-relaxation (ZF-{\boldmath $μ$}SR) measurements were carried out down to 80 mK on the randomness bond system Tl$_{1-x}$K$_x$CuCl$_3$ with $x$ = 0.44. Time spectra are well fitted by the stretched exponential function $\exp (-λt)^β$. The muon spin relaxation rate $λ$ increases rapidly with decreasing temperature, and $β$ tends to 0.5 at 80 mK. The divergent increase of $λ$ suggests the critical slowing down of the frequency of the Cu-3{\it d} spin fluctuations toward a spin frozen state below 80 mK, and the root-exponential-like behavior of the time spectrum indicates that the origin of the relaxation is possibly the spatially-fixed fluctuating dilute moments.

cond-mat.str-el↗
arXiv2007

Higher order Painleve system of type D^{(1)}_{2n+2} arising from integrable hierarchy

A higher order Painleve system of type D^{(1)}_{2n+2} was introduced by Y. Sasano. It is an extension of the sixth Painleve equation for the affine Weyl group symmetry. It is also expressed as a Hamiltonian system of order 2n with a coupled Painleve VI Hamiltonian. In this paper, we discuss a derivation of this system from a Drinfeld-Sokolov hierarchy.

math-ph↗
arXiv2007

Coupled Painleve VI system with E_6^{(1)} symmetry

We present an new system of ordinary differential equations with affine Weyl group symmetry of type E_6^{(1)}. This system is expressed as a Hamiltonian system of sixth order with a coupled Painleve VI Hamiltonian.

math-ph↗
arXiv2007

1H-NMR Study on the Magnetic Order in the Mixture of Two Spin Gap Systems (CH3)2CHNH3CuCl3 and (CH3)2CHNH3CuBr3

The antiferromagnetic ordering in the solid-solution of the two spin-gap systems (CH3)2CHNH3CuCl3 and (CH3)2CHNH3CuBr3 has been investigated by 1H-NMR. The sample with the Cl-content ratio x=0.85 showed a clear splitting in spectra below TN=13.5 K, where the spin-lattice relaxation rate T1-1 showed a diverging behavior. The critical exponent of the temperature dependence of the hyperfine field is found to be 0.33.

cond-mat.str-el↗
arXiv2006

Impurity-induced magnetic order in the mixture of two spin gap systems (CH3)2CHNH3CuCl3 and (CH3)2CHNH3CuBr3

The ground state of the solid solution of the two spin gap systems (CH3)2CHNH3CuCl3 and (CH3)2CHNH3CuBr3 has been investigated by 1H-NMR. The existence of a magnetic ordering in the sample with the Cl-content x=0.85 was clearly demonstrated by a drastic splitting in a resonance line at low temperatures below TN=13.5K. The observed NMR spectra in the ordered state was qualitatively consistent with the simple antiferromagnetic state.

cond-mat.other↗
arXiv2005

Ubiquity of Log-normal Distributions in Intra-cellular Reaction Dynamic

The discovery of two fundamental laws concerning cellular dynamics with recursive growth is reported. First, the chemical abundances measured over many cells are found to obey a log-normal distribution and second, the relationship between the average and standard deviation of the abundances is found to be linear. The ubiquity of the laws is explored both theoretically and experimentally. First by means of a model with a catalytic reaction network, the laws are shown to appear near the critical state with efficient self-reproduction. Second by measuring distributions of fluorescent proteins in bacteria cells the ubiquity of log-normal distribution of protein abundances is confirmed. Relevance of these findings to cellular function and biological plasticity is briefly discussed.

q-bio.MN↗
arXiv2005

Affine Weyl group symmetry of the Garnier system

We show that the Garnier system in n-variables has affine Weyl group symmetry of type $B^{(1)}_{n+3}$. We also formulate the $τ$ functions for the Garnier system (or the Schlesinger system of rank 2) on the root lattice $Q(C_{n+3})$ and show that they satisfy Toda equations, Hirota-Miwa equations and bilinear differential equations.

math-ph↗