Minoru Yamashita 교수

The nature of quantum spin liquids, a novel state of matter where strong quantum fluctuations destroy the long-range magnetic order even at zero temperature, is a long-standing issue in physics. We measured the low-temperature thermal conductivity of the recently discovered quantum spin liquid candidate, the organic insulator EtMe3Sb[Pd(dmit)2]2. A sizable linear temperature dependence term is clearly resolved in the zero-temperature limit, indicating the presence of gapless excitations with an

We have investigated the sample dependence of the half-integer thermal Hall effect in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ under a magnetic field tilted ${45}^{\ensuremath{\circ}}$ from the $c$ axis to the $a$ axis. We find that the sample with the largest longitudinal thermal conductivity ${\ensuremath{\kappa}}_{xx}$ shows the half-integer quantized thermal Hall effect expected in the Kitaev model. On the other hand, the quantized thermal Hall effect was not observed in

The structure of the superconducting order parameter in the iron-pnictide superconductor BaFe${}_{2}$(As${}_{0.67}$P${}_{0.33}$)${}_{2}$ (${T}_{c}=31$ K) with line nodes is studied by the angle-resolved thermal conductivity measurements in a magnetic field rotated within the basal plane. We find that the thermal conductivity displays distinct fourfold oscillations with minima when the field is directed at $\ifmmode\pm\else\textpm\fi{}{45}^{\ensuremath{\circ}}$ with respect to the tetragonal $a$

Quantized vortices with half-integer circulation, which are forbidden from existing in a conventional superfluid because of the single valueness of the wave function, are theoretically predicted to exist in superfluid 3He-A if the order parameters l over and d over form l over perpendicular d over texture. To form the l over perpendicular d over texture, we confined the superfluid between parallel plates with a 12.5 microm gap and applied a magnetic field of H=26.7 mT perpendicular to the plates

The superconducting gap structure of LaFePO $({T}_{c}=7.4\text{ }\text{K})$ is studied by thermal conductivity $(\ensuremath{\kappa})$ at low temperatures in fields $H$ parallel and perpendicular to the $c$ axis. A clear two-step field dependence of $\ensuremath{\kappa}(H)$ with a characteristic field ${H}_{s}(\ensuremath{\sim}350\text{ }\text{Oe})$ much lower than the upper critical field ${H}_{c2}$ is observed. In spite of the large anisotropy of ${H}_{c2}$, $\ensuremath{\kappa}(H)$ in both $H

The presence or absence of itinerant gapless excitations in the organic quantum spin liquid (QSL) candidate EtMe${}_{3}$Sb[Pd(dmit)${}_{2}$]${}_{2}$, probed by a finite residual linear term in the thermal conductivity ${\ensuremath{\kappa}}_{0}/T$, has been a controversial hot topic. Here, the authors find that ${\ensuremath{\kappa}}_{0}/T$ strongly depends on the cooling process. A finite ${\ensuremath{\kappa}}_{0}/T$ is observed in a slowly cooled sample, but not in a rapidly cooled sample. Th

Quantum spin liquids (QSLs) are fluidlike states of quantum spins in which the long-range ordered state is destroyed by quantum fluctuations. The ground state of QSLs and their exotic phenomena, which have been extensively discussed for decades, have yet to be identified. We employ thermal-transport measurements on newly discovered QSL candidates κ-(BEDT-TTF)(2)Cu(2)(CN)(3) and EtMe(3)Sb[Pd(dmit)(2)](2), and report that the two organic insulators have different QSLs characterized by different el