相关论文: The field-induced magnetic ordering transition in …
The recent observation [Oosawa et al. J. Phys. : Condens. Matter {\bf 11}, 265 (1999)] of the field-induced N\'{e}el ordering in a spin-gap magnetic compound TlCuCl$_3$ is interpreted as a Bose-Einstein Condensation of magnons. A mean-field…
A quantitative study of the field-induced magnetic ordering in TlCuCl$_3$ in terms of a Bose-Einstein condensation (BEC) of magnons is presented. It is shown that the hitherto proposed simple BEC scenario is in quantitative and qualitative…
Magnetization measurements were performed to investigate the critical behavior of the field-induced magnetic ordering in gapped spin system TlCuCl$_3$. The critical density of the magnons was obtained as a function of temperature and the…
KCuCl$_3$ is a three-dimensional coupled spin-dimer system and has a singlet ground state with an excitation gap ${\Delta}/k_{\rm B}=31$ K. High-field magnetization measurements for KCuCl$_3$ have been performed in static magnetic fields of…
We investigated experimentally and theoretically sound attenuation in the quantum spin system TlCuCl_3 in magnetic fields at low temperatures. Near the point of Bose-Einstein condensation (BEC) of magnons a sharp peak in the sound…
Neutron elastic scattering experiments have been performed on the spin gap system TlCuCl$_3$ in magnetic fields parallel to the $b$-axis. The magnetic Bragg peaks which indicate the field-induced N\'{e}el ordering were observed for magnetic…
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…
The magnetic properties of the interacting dimer system TlCuCl3 are investigated within a bond-operator formulation. The observed field-induced staggered magnetic order perpendicular to the field is described as a Bose condensation of…
In the first part we discuss how the BEC picture for magnons is modified by anisotropies induced by spin-orbit coupling. In particular we focus on the effects of antisymmetric spin interactions and/or a staggered component of the $g$…
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…
Motivated by recent experiments on Ba$_{3}$Cr$_{2}$O$_8$, a new spin-dimer compound with spin-1/2 moments of Cr$^{5+}$ ions, we theoretically investigate the field-induced magnetic ordering in this material in view of the Bose-Einstein…
The effect of randomness on field-induced magnetic ordering was investigated through specific heat measurements in Tl$_{1-x}$K$_x$CuCl$_3$ with $x\leq 0.22$. The isostructural parent compounds TlCuCl$_3$ and KCuCl$_3$ are coupled spin dimer…
Specific heat measurements have been performed in the coupled dimer system TlCuCl$_3$, which has a singlet ground state with the excitation gap $\Delta \simeq 7.5$K. The cusplike anomaly indicative of the 3D magnetic ordering was clearly…
We describe the Bose-Einstein condensate of magnetic bosonic quasiparticles in insulating spin systems using a phenomenological standard functional method for T = 0. We show that results that are already known from advanced computational…
Starting from a phenomenological standard energy functional to describe the condensation of a dilute gas of bosonic quasiparticles in magnetic insulators, we find that the inclusion of a perturbation term that explicitly violates the axial…
The effect of exchange bond randomness on the ground state and the field-induced magnetic ordering was investigated through magnetization measurements in the spin-1/2 mixed quantum spin system (Tl$_{1-x}$K$_{x}$)CuCl$_3$ for $x<0.36$. Both…
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…
Combined experimental and modeling studies of the magnetocaloric effect, ultrasound, and magnetostriction were performed on single-crystal samples of the spin-dimer system Sr$_3$Cr$_2$O$_8$ in large magnetic fields, to probe the…
High-field magnetic torque measurements were carried out in the spin gap system (CH$_3$)$_2$CHNH$_3$CuCl$_3$. It was observed that the magnitude of the magnetic torque $\tau$ is almost zero until the critical field and then increases…
The field-induced magnetic order in the singlet-ground-state system CsFeCl$_3$ has been studied by measuring magnetization and neutron diffraction. The field dependence of intensity for the neutron magnetic reflection has clearly…