Related papers: Collective spin 1 singlet phase in high pressure o…
In the frameworks of a nesting model for Q1D organic conductor at the antiferromagnetic (SDW) quantum critical point the first-order transition separates metallic state from the soliton phase having the periodic domain structure. The low…
We report the first experimental evidence for a metallic phase in fluid molecular oxygen. Our electrical conductivity measurements of fluid oxygen under dynamic quasi-isentropic compression show that a non-metal/metal transition occurs at…
We give a general introduction to quantum phase transitions in strongly-correlated electron systems. These transitions which occur at zero temperature when a non-thermal parameter $g$ like pressure, chemical composition or magnetic field is…
Using the spin-wave approximation, we study the geometric phase (GP) of a central spin (signal qubit) coupled to an antiferromagnetic (AF) environment under the application of an external global magnetic field. The external magnetic field…
Condensates of spin-1 sodium display rich spin dynamics due to the antiferromagnetic nature of the interactions in this system. We use Faraday rotation spectroscopy to make a continuous and minimally destructive measurement of the dynamics…
X-ray diffraction studies to ~90 GPa at room temperature show that Fe$_{2}$TiO$_{4}$ ferrous inverse spinel undergoes the following sequence of structural transitions : cubic (Fd3m) to tetragonal (I41/amd)to orthorhombic(Cmcm) to…
The low-energy effective Hamiltonian of three coupled spin chains with periodic boundary conditions (spin tube) is expressed, in the limit of strong interchain coupling, in terms of XXZ chains coupled by biquadratic exchange interaction. A…
We apply the finite-temperature variational cluster approach to a strongly correlated and spin-orbit coupled model for four electrons (i.e. two holes) in the $t_{2g}$ subshell. We focus on parameters suitable for antiferromagnetic Mott…
We compute the phase diagram of strongly interacting fermions in one dimension at finite temperature, with mass and spin imbalance. By including the possibility of the existence of a spatially inhomogeneous ground state, we find regions…
High-pressure and high-field electron spin resonance (ESR) measurements have been performed on a single crystal of the orthogonal-dimer spin system SrCu$_{2}$(BO$_{3}$)$_{2}$. With frequencies below 1 THz, ESR signals associated with…
We propose a unified magnetic phase diagram of cuprate superconductors. A new feature of this phase diagram is a broad intermediate doping region of quantum-critical, $z=1$, behavior, characterized by temperature independent $T_1T/T_{\rm…
Oxygen isotope substitution is performed in the perovskite cobalt oxide (Pr$_{0.7}$Sm$_{0.3}$)$_{0.7}$Ca$_{0.3}$CoO${_3}$ which shows a sharp spin state transition from the intermediate spin (IS) state to the low spin (LS) state at a…
We report high pressure structural phase transformation sequence in a layered Iron-based superconducting compound FeSe0.3Te0.7 to 31 GPa at room temperature. The ambient pressure PbO type tetragonal phase (Space Group - P4/nmm) transforms…
In addition to signals for the critical point, evidence for a first order phase transition would indicate a nontrivial structure within the QCD phase diagram. Moreover, while not a direct measurement of the critical point, the presence of a…
Spin-1 bosons on a 1-dimensional chain, at incommensurate filling with anti-ferromagnetic spin interaction between neighboring bosons, may form a spin-1 boson condensed state that contains both gapless charge and spin excitations. We argue…
The Kitaev model with an applied magnetic field in the $H||[111]$ direction shows two transitions: from a non-abelian gapped quantum spin liquid (QSL) to a gapless QSL at $H_{c1} \simeq 0.2K$ and a second transition at a higher field…
We propose an effective theory for the critical phase of a quantum ferrimagnetic chain with alternating spins 1 and 1/2 in an external magnetic field. With the help of the matrix product variational approach, the system is mapped to a…
We use the density matrix renormalization group method(DMRG) and the infinite time evolved block decimation method(iTEBD) to investigate the ground states of the spin-orbit coupled Fermi gas in a one dimensional optical lattice with a…
Spin-crossover molecules having a low-spin ground state and a low-lying excited high-spin state are promising components for molecular electronics. We theoretically examine one-dimensional spin-crossover chain molecules of the type of Fe-II…
We experimentally demonstrate that combining a cubic optical lattice with a spinor Bose-Einstein condensate substantially relaxes three strict constraints and brings spin singlets of ultracold spin-1 atoms into experimentally accessible…