Related papers: Mott and spin-Peierls physics in TiPO$_4$ under hi…
Mott-insulating transition metal oxides containing $t_{2g}^4$ ions with strong spin-orbit coupling were recently demonstrated to display unusual magnetism due to a dynamical mixing of the low-energy multiplet states via exchange processes.…
We study a bandwidth controlled Mott metal-insulator transition (MIT) between a Fermi liquid metal and a quantum spin-liquid insulator at half-filling in three dimensions (3D). Using a slave rotor approach, and incorporating gauge field…
Polarized infrared reflectivity measurements have been performed on single crystals of the spin-Peierls compound alpha'-NaV2O5 in the temperature range 20-300 K. Pronounced spectral features associated with the formation of the dimerized…
We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report…
The iso-electronic $d^{4}$ compounds of the $4d$ series show rich phase diagrams due to competing spin, charge and orbital degrees of freedom in presence of strong correlations and structural distortions. One such iso-electronic series,…
Spin and charge fluctuations at vicinity of metal-to-Mott insulator transitions are studied in an organic solid with molecular dimers. The extended Hubbard model taking account of the internal electronic degree of freedom in a molecular…
For quantum electronics, the possibility to finely tune the properties of magnetic topological insulators (TIs) is a key issue. We studied solid solutions between two isostructural Z$_2$ TIs, magnetic MnBi$_2$Te$_4$ and nonmagnetic…
FePS$_3$ is a prototype van der Waals layered antiferromagnet and a Mott insulator under ambient conditions, which has been recently reported to go through a pressure-induced dimensionality crossover and an insulator-to-metal transition.…
Transition metal oxides such as vanadium dioxide (VO$_2$), niobium dioxide (NbO$_2$), and titanium sesquioxide (Ti$_2$O$_3$) are known to undergo a temperature-dependent metal-insulator transition (MIT) in conjunction with a structural…
On the basis of experimental thermoelectric power results and ab initio calculations, we propose that a metal-insulator transition takes place at high pressure (approximately 6 GPa) in MgV_2O_4.
Within the framework of a realistic multi-band p-d-model, we derived an effective Hamiltonian to describe the exchange interaction effects near the spin crossover in magnetic Mott-Hubbard insulators under pressure. It is shown that…
We have studied the crystal structure and magnetic properties of the organic radical cation salt, BBDTA-InCl4. This material formed a one-dimensional coordination polymer, whose structure was characteristic of inorganic spin-Peierls…
CuGeO$_3$ has long been studied as a prototypical example of the spin-Peierls transition in a $S = 1/2$ Heisenberg chain. Despite intensive investigation of this quasi-one-dimensional material, systematic measurements and calculations of…
We study a new version of the one-dimensional spin-orbital model with spins S=1 relevant to cubic vanadates. At small Hund's coupling J_H we discover dimerization in a pure electronic system solely due to a dynamical spin-orbital coupling.…
Transport and magnetic measurements and structural and NMR studies have been carried out on (Pr1-yR'y)1-xAxCoO3 {R'=(rare earth elements and Y); A=(Ca, Ba and Sr)} at ambient pressure or under high pressure. The system exhibits a phase…
This thesis investigates a transformation path between the Th3P4-type and the spinel-type structures of hafnium (IV) and titanium (IV) nitride, M3N4 (M = Hf, Ti) with computational methods. For both compounds, the Th3P4-type was synthesized…
We theoretically describe the charge ordering (CO) metal-insulator transition based on a quasi-one-dimensional extended Hubbard model, and investigate the finite temperature ($T$) properties across the transition temperature, $T_{\rm CO}$.…
${\lambda}$-RhO$_2$, a prototype 4d transition metal oxide, has been prepared by oxidative delithiation of spinel LiRh$_2$O$_4$ using ceric ammonium nitrate. Average-structure studies of this RhO$_2$ polytype, including synchrotron powder…
The temperature dependence of the Mott metal-insulator transition (MIT) is studied with a VO_2-based two-terminal device. When a constant voltage is applied to the device, an abrupt current jump is observed with temperature. With increasing…
The physics of the spin glass (SG) state, with magnetic moments (spins) frozen in random orientations, is one of the most intriguing problems in condensed matter physics. While most theoretical studies have focused on the Edwards-Anderson…