arXiv subjects

Hiroyuki K. Yoshida

Publications and source records attributed to Hiroyuki K. Yoshida.

5 recordsLinked to original sources

arXiv2026

Magnetism and Electrical Conduction in Lightly-Doped Single-Layer High-$T_c$ Cuprate $\mathrm{La}_2\mathrm{CuO}_{4+δ}$

The temperature dependences of magnetization and electrical resistivity as well as their magnetic field dependences have been examined in lightly-doped single-layer cuprate $\mathrm{La}_2\mathrm{CuO}_{4+δ}$ (LCO, hole-doping level $p \, (2δ) \cong 0.03$) single crystals, in comparison with those in the extremely low doping region of $p \lesssim 0.015$ to uncover the intrinsic magnetism and electrical conduction of the $\mathrm{Cu\text{-}O}$ plane that exhibits both antiferromagnetic (AF) and superconducting (SC) orders simultaneously. In $p \cong 0.03$ SC LCO, the sub-lattice moments on $\mathrm{Cu}$ sites and their AF couplings are only $\sim 15\,\%$ smaller than those of the Mott-insulator parent material, suggesting that the localization of $\mathrm{Cu}$ $3d$ electrons remains very strong. Furthermore, we report that in the SC LCO, two-dimensional AF spin correlations develop rapidly from $T^* \cong 280\text{ K}$ towards Néel temperature $T_{\mathrm{N}} = 266\text{ K}$, where the out-of-plane resistivity starts to decrease largely. This might be responsible for the AF ordering at such a high temperature in the SC single-layer cuprate with $p \cong 0.03$.

cond-mat.supr-con↗

arXiv2025

Magnetic excitations in the 1/3 plateau state in InCu$_3$(OH)$_6$Cl$_3$

Magnetic dynamics in InCu$_3$(OH)$_6$Cl$_3$ was investigated from the NMR relaxation rate measurement. In InCu$_3$(OH)$_6$Cl$_3$, the magnetization isotherm shows a plateau at the 1/3 of full-saturation magnetization, characterizing the 1/3 plateau state. As the 1/3 plateau state appears above 7 T upto 14 T, the microscopic magnetic properties were investigated with the NMR measurement in steady fields. The temperature and field dependence of $1/T_1$ measurement reveals a gap in the magnetic excitation spectrum and its evolution with field in the 1/3 plateau state. The field dependence of spin gap provides an important information to understand the microscopic origin of 1/3 plateau state in the kagome antiferromagnets.

cond-mat.str-el↗

arXiv2021

Observation of domain wall bimerons in chiral magnets

Topological defects embedded in or combined with domain walls have been proposed in various systems, some of which are referred to as domain wall skyrmions or domain wall bimerons. However, the experimental observation of such topological defects remains an ongoing challenge. Here, using Lorentz transmission electron microscopy, we report the experimental discovery of domain wall bimerons in chiral magnet Co-Zn-Mn(110) thin films. By applying a magnetic field, multidomain structures develop, and simultaneously, chained and isolated bimerons arise as the localized state between the domains with the opposite in-plane components of net magnetization. The multidomain formation is attributed to magnetic anisotropy and dipolar interaction, and domain wall bimerons are stabilized by the Dzyaloshinskii-Moriya interaction. In addition, micromagnetic simulations show that domain wall bimerons appear for a wide range of conditions in chiral magnets with cubic magnetic anisotropy. Our results promote further study in various fields of physics.

cond-mat.mtrl-sci↗

arXiv2021

Magnetic properties of the Shastry-Sutherland lattice material BaNd$_2$ZnO$_5$

We investigate the physical properties of the Shastry-Sutherland lattice material BaNd$_2$ZnO$_5$. Neutron diffraction, magnetic susceptibility, and specific heat measurements reveal antiferromagnetic order below 1.65 K. The magnetic order is found to be a 2-$\boldsymbol{Q}$ magnetic structure with the magnetic moments lying in the Shastry-Sutherland lattice planes comprising the tetragonal crystal structure of BaNd$_2$ZnO$_5$. The ordered moment for this structure is 1.9(1) $μ_B$ per Nd ion. Inelastic neutron scattering measurements reveal that the crystal field ground state doublet is well separated from the first excited state at 8 meV. The crystal field Hamiltonian is determined through simultaneous refinement of models with both the LS coupling and intermediate coupling approximations to the inelastic neutron scattering and magnetic susceptibility data. The ground state doublet indicates that the magnetic moments lie primarily in the basal plane with magnitude consistent with the size of the determined ordered moment.

cond-mat.str-el↗

arXiv2021

Emergence of Frustrated Short-Range Order above Long-Range Order in the $S=1/2$ Kagome Antiferromagnet CaCu$_3$(OD)$_6$Cl$_2\cdot0.6$D$_2$O

We report on the low-energy dynamics in the kagome antiferromagnet CaCu$_3$(OD)$_6$Cl$_2\cdot0.6$D$_2$O (Ca-kapellasite) as studied by use of $^2$D-NMR measurements. Previous $^{35}$Cl-NMR measurements revealed that the nuclear spin-lattice relaxation rate ($1/T_1$) shows two peaks at temperatures, $T^{\ast} = 7.2$ K and $T_s \simeq 25$ K. While the low-temperature peak at $T^{\ast}$ is ascribed to the critical fluctuations near the long-range magnetic ordering, the origin of the high-temperature peak has not been fully understood. From the $1/T_1$ measurements on the D sites at the OD groups (D$_{\rm OD}$), we find no peak at $T_s$, evidencing that the high-temperature peak is not related to the molecular dynamics of the OD groups. We discuss the possibility of a frustration-induced short-range ordered state below $T_s$ before the long-range order is stabilized by the Dzyaloshinskii-Moriya interaction. We also observed static internal fields at the D$_{\rm OD}$ site in the long-range ordered state below $T^{\ast}$, and confirm the previously proposed negative-chirality $q=0$ magnetic structure.

cond-mat.str-el↗