Parity-broken ground state for the spin-1 pyrochlore antiferromagnet

The ground-state properties of the spin-1 pyrochlore antiferromagnet are studied by applying the VBS-like tetrahedron-unit decomposition to the original spin system. The symmetrization required on every vertex is taken into account by introducing a ferromagnetic coupling. The pairwise effective Hamiltonian between the adjacent tetrahedrons is obtained by considering the next nearest neighbor and the third neighbor exchange interactions. We find that the transverse component of the spin chirality exhibits a long-range order, breaking the parity symmetry of the tetrahedral group, while the chirality itself is not broken.Comment: 4 pages, 3 figures, REVTeX(ver.3.1

Microscopic Calculation of Spin Torques and Forces

Spin torques, that is, effects of conduction electrons on magnetization dynamics, are calculated microscopically in the first order in spatial gradient and time derivative of magnetization. Special attention is paid to the so-called \beta-term and the Gilbert damping, \alpha, in the presence of electrons' spin-relaxation processes, which are modeled by quenched magnetic impurities. Two types of forces that the electric/spin current exerts on magnetization are identified based on a general formula relating the force to the torque.Comment: Proceedings of ICM2006 (Kyoto), to appear in J. Mag. Mag. Ma

Anomalous Hall effect as a probe of the chiral order in spin glasses

Anomalous Hall effect arising from the noncoplanar spin configuration (chirality) is discussed as a probe of the chiral order in spin glasses. It is shown that the Hall coefficient yields direct information about the linear and nonlinear chiral susceptibilities of the spin sector, which has been hard to obtain experimentally from the standard magnetic measurements. Based on the chirality scenario of spin-glass transition, predictions are given on the behavior of the Hall resistivity of canonical spin glasses.Comment: Order estimate of the effect given, one reference added. To appear in Phys. Rev. Letter

Magnetism in Kitaev Quantum Spin Liquid Candidate RuBr3_3

The present studies show that long-range magnetic order takes place in RuBr$_3$ at $\approx$ 34 K. The observations of clear oscillations in the muon time spectra demonstrate the presence of well-defined internal fields at the muon sites. The magnetic ordering appears to be very robust and static suggesting a more conventional nature of magnetic ordering in the RuBr$_3$ system at zero field. Present investigations prove that in RuBr$_3$ the Kitaev interactions are likely to be weakened at zero field in comparison to the $\alpha$-RuCl$_3$ system. This proves that it is possible to tune the Kitaev interactions by replacing Cl with heavier halogen elements such as Br.Comment: 5 pages, 5 figure

Primary Bone Formation in Porous Hydroxyapatite Ceramic: A Light and Scanning Electron Microscopic Study

Porous hydroxyapatite ceramics combined with rat marrow cells were implanted subcutaneously in the back of syngeneic Fischer rats . Fluorochrome-labeling (calcein, tetracycline) was performed post-operatively and the ceramics were harvested 4 weeks after implantation. Undecalcified thin sections of the implants were observed under light microscopy or fluoromicroscopy and the corresponding areas were also analyzed in a scanning electron microscope connected to an electron probe microanalyzer (SEM-EPMA). Many pore areas of the ceramics showed bone and osteoid formation together with active osteoblasts. The bone formation began directly on the surface of the ceramic and proceeded in a centripetal direction towards the center of the pores. SEM-EPMA analysis revealed continuous high levels of calcium and phosphorus in bone/ceramic interface and a gradual decrease of these levels in the osteoid region. These results indicate that the interaction between osteoblasts and ceramic surface resulted in bone formation

Dexamethasone-loaded carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles enhances bone formation in vivo

[Excerpt] Dexamethasone-loaded carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles, CMC/PAMAM-Dex were successfully synthesized to find applications as a controlled system of relevant molecules in Bone Tissue Engineering. These are aimed at modulatingtheproliferation anddifferentiationofstem cells,both invitro and in vivo. In previous work, we have demonstrated that CMC/ PAMAM-Dex nanoparticles are internalized with high efficiency by different cell types, namely osteoblastic-cells, SaOs-2 and rat bone marrow stromal cells, RBMSCs. The biocompatibility of HA and SPCL scaffolds was also assessed by means of seeding RBMSCs onto the materials and performing a luminescent cell viability assay, after 24 and 72hrs. [...]info:eu-repo/semantics/publishedVersio