Related papers: NMR evidence for a strong modulation of the Bose-E…
In order to understand the nature of the two-dimensional Bose-Einstein condensed (BEC) phase in BaCuSi2O6, we performed detailed 63Cu and 29Si NMR above the critical magnetic field, Hc1= 23.4 T. The two different alternating layers present…
The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S = 1/2 moments on a quasi-2D square lattice. We have investigated its spin dynamics by inelastic neutron scattering experiments on single crystals with an energy…
We report an experimental determination of the phase boundary between a quantum paramagnetic state and the proposed spin Bose-Einstein condensate of triplons in the spin gap compound BaCuSi2O6. The ordering temperature is related to the…
We report on results of specific heat measurements on single crystals of the frustrated quasi-2D spin-1/2 antiferromagnet Cs_2CuCl_4 (T_N=0.595 K) in external magnetic fields B<12 T and for temperatures T>30 mK. Decreasing B from high…
We synthesized single crystals of composition Ba$_2$CuSi$_2$O$_6$Cl$_2$ and investigated its quantum magnetic properties. The crystal structure is closely related to that of the quasi-two-dimensional (2D) dimerized magnet BaCuSi$_2$O$_6$…
Nuclear magnetic resonance (NMR) study of the high magnetic field (H) part of the Bose-Einstein condensed (BEC) phase of the quasi-onedimensional (quasi-1D) antiferromagnetic quantum spin-chain compound NiCl2-4SC(NH2)2 (DTN) was performed.…
We apply density functional theory band structure calculations and quantum Monte Carlo simulations to investigate the Bose-Einstein condensation in the spin-1/2 quantum magnet Pb2V3O9. In contrast to previous conjectures on the…
Thermodynamics of spin dimer system BaCuSi_2O_6 is studied using a quantum Monte Carlo calculation (QMC) and a bond-operator mean field theory. We propose that a new type of boson, which, rather than being hard-core, allows up to two…
We study the spin dynamics in the quasi-2D spin-$1/2$ dimer compound Ba$_2$CuSi$_2$O$_6$Cl$_2$, which exhibits a magnetic field-induced Bose-Einstein condensate (BEC) of triplons. Using nuclear magnetic resonance (NMR) spin-lattice…
Bose-Einstein condensation (BEC) underpins exotic forms of order ranging from superconductivity to superfluid 4 He. In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the BEC of magnon…
It has recently been suggested that the organic compound NiCl$_2$-4SC(NH$_2$)$_2$ (DTN) exhibits Bose-Einstein Condensation (BEC) of the Ni spin degrees of freedom for fields applied along the tetragonal c-axis. The Ni spins exhibit 3D…
The apparent metal-insulator transition is observed in a high quality two-dimensional electron system (2DES) in the strained Si quantum well of a Si/Si_{1-x}Ge_x heterostructure with mobility \mu=1.9 x 10^5 cm^2/Vs at density n=1.45 x…
K$_2$CuF$_4$ is magnetically described as a spin-1/2, quasi-two-dimensional (2D), square-lattice XXZ ferromagnet with weak easy-plane anisotropy. The magnetic ordering for an applied magnetic field $H$ parallel to the $c$ axis is equivalent…
BaCuSi$_2$O$_6$ is a quasi-two-dimensional (2D) quantum antiferromagnet containing three different types of stacked, square-lattice bilayer hosting spin-1/2 dimers. Although this compound has been studied extensively over the last two…
Based on a realistic spin Hamiltonian for a frustrated quasi-two dimensional spin-1/2 antiferromagnet Cs$_{2}$CuCl$_{4}$, a three-dimensional spin ordering in the applied magnetic field $B$ near the saturation value $B_{c}$ is studied…
In ordered magnets, the elementary excitations are spin waves (magnons), which obey Bose-Einstein statistics. Similarly to Cooper pairs in superconductors, magnons can be paired into bound states under attractive interactions. The Zeeman…
The quantum magnet NiCl$_2$-4SC(NH$_2$)$_2$ is a candidate for observing Bose-Einstein Condensation of spin degrees of freedom in applied magnetic fields. An XY antiferromagnetic ordered state occurs in a dome-shaped region of the…
Building on recent NMR experiments [Phys. Rev. Lett. 118, 067203], we theoretically investigate the high magnetic field regime of the disordered quasi-one-dimensional $S=1$ antiferromagnetic material…
The dimerized S=1/2 spins of the Cu ions in TlCuCl3 are ordered antiferromagnetically in the presence of a field larger than about 54 kOe in the zero-temperature limit. Within the mean-field approximation all thermal effects are frozen out…
Quantum magnets offer a unique platform for exploring exotic quantum phases and quantum phase transitions through external magnetic fields. A prominent example is the field-induced Bose--Einstein condensation (BEC) of magnons near the…