Related papers: Spectroscopic evidence for possible quantum spin l…
The Mott insulator $\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_3$ forms a highly-frustrated triangular lattice of $S=1/2$ dimers with a possible quantum-spin-liquid state. Our experimental and numerical studies reveal the emergence of a slight…
Systematic pressure- and temperature-dependent infrared studies on the two-dimensional organic quantum spin-liquid $\beta^{\prime}$-EtMe$_3$Sb[Pd(dmit)$_2$]$_2$ disclose the electronic and lattice evolution across the Mott insulator-metal…
Quantum spin liquids are fascinating phases of matter, hosting fractionalized spin excitations and unconventional long-range quantum entanglement. These exotic properties, however, also render their experimental characterization…
The competition between electron localization and de-localization in Mott insulators underpins the physics of strongly-correlated electron systems. Photo-excitation, which re-distributes charge between sites, can control this many-body…
Resonant inelastic light scattering experiments access the low lying excitations of electron liquids in the fractional quantum Hall regime in the range $2/5 \geq \nu \geq 1/3$. Modes associated with changes in the charge and spin degrees of…
Pursuing fractionalized particles that do not bear properties of conventional measurable objects, exemplified by bare particles in the vacuum such as electrons and elementary excitations such as magnons, is a challenge in physics. Here we…
We present a comprehensive experimental investigation of the temperature evolution of magnetic states in triangular-lattice delafossite YbCuSe$_2$. Magnetization measurements on high-quality single crystals reveal easy-plane anisotropy.…
The localized (particle-like) correlated electrons deserve particular attention as they govern various exotic quantum phenomena, such as quantum spin liquids, Wigner crystals, and Mott insulators in correlated systems. However, direct…
Recent studies have revealed that the randomness-induced quantum spin liquid (QSL)-like state is stabilized in certain frustrated quantum magnets in two and three dimensions. In order to clarify the nature of this gapless QSL-like state, we…
We study the Mott transition from a metal to cluster Mott insulators in the 1/4- and 1/8-filled pyrochlore lattice systems. It is shown that such Mott transitions can arise due to charge localization in clusters or in tetrahedron units,…
Non-local correlation effects in the half-filled Hubbard model on an isotropic triangular lattice are studied within a spin polarized extension of the dual fermion approach. A competition between the antiferromagnetic non-collinear and the…
Quantum spin liquids are exotic Mott insulators that carry extraordinary spin excitations and thus, when doped, expected to afford novel metallic states coupled to the unconventional magnetic excitations. The organic triangular-lattice…
We evaluate the spin density oscillations arising in quantum spin Hall quantum dots created via two localized magnetic barriers. The combined presence of magnetic barriers and spin-momentum locking, the hallmark of topological insulators,…
The spin dynamics of electron doped Mott insulators on a triangular lattice is studied based on the $t-J$ model. It is found that the particularly universal behaviors of integrated dynamical spin structure factor seen in the doped Mott…
The weak Mott insulating regime of the triangular lattice Hubbard model exhibits a rich magnetic phase diagram as a result of the ring exchange interaction in the spin Hamiltonian. These phases include the Kalmeyer-Laughlin type chiral spin…
A family of spin-orbit coupled honeycomb Mott insulators offers a playground to search for quantum spin liquids (QSLs) via bond-dependent interactions. In candidate materials, a symmetric off-diagonal $\Gamma$ term, close cousin of Kitaev…
We show that the off-diagonal exchange anisotropy drives Mott insulators with strong spin-orbit coupling to a classical spin liquid regime, characterized by an infinite number of ground states and Ising variables living on closed or open…
Spin-liquid behavior was recently suggested experimentally in the moderately one-dimensional organic compound $\kappa$-H$_3$(Cat-EDT-TTF)$_2$. This compound can be modeled by the one-band Hubbard model on the anisotropic triangular lattice…
Organic solids host various electronic phases. Especially, a milestone compound of organic solid, $\beta'$-$X$[Pd(dmit)$_2$]$_2$ with $X$=EtMe$_3$Sb shows quantum spin-liquid (QSL) properties suggesting a novel state of matter. However,…
A quantum spin liquid (QSL) is an exotic state in which electron spins are highly entangled, yet keep fluctuating even at zero temperature. Experimental realization of model QSLs has been challenging due to imperfections, such as antisite…