Hybridization-driven gap in U3Bi4Ni3: a 209Bi NMR/NQR study

We report 209Bi NMR and NQR measurements on a single crystal of the Kondo insulator U3Bi4Ni3. The 209Bi nuclear spin-lattice relaxation rate ($T_1^{-1}$) shows activated behavior and is well-fit by a spin gap of 220 K. The 209Bi Knight shift (K) exhibits a strong temperature dependence arising from 5f electrons, in which K is negative at high temperatures and increases as the temperature is lowered. Below 50 K, K shows a broad maximum and decreases slightly upon further cooling. Our data provide insight into the evolution of the hyperfine fields in a fully gapped Kondo insulator based on 5f electron hybridization.Comment: 4 pages, 4 figures, submitted to Phys. Rev.

Uncovering the Hidden Order in URu2Si2 by Impurity Doping

We report the use of impurities to probe the hidden order parameter of the strongly correlated metal URu_2Si_2 below the transition temperature T_0 ~ 17.5 K. The nature of this order parameter has eluded researchers for more than two decades, but is accompanied by the development of a partial gap in the single particle density of states that can be detected through measurements of the electronic specific heat and nuclear spin-lattice relaxation rate. We find that impurities in the hidden order phase give rise to local patches of antiferromagnetism. An analysis of the coupling between the antiferromagnetism and the hidden order reveals that the former is not a competing order parameter but rather a parasitic effect of the latter.Comment: 4 pages, 4 figure

Production and detection of doubly charmed tetraquarks

The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d} tetraquark we show that in present (SELEX, Tevatron, RHIC) and future facilities (LHCb, ALICE) the production rate is promising and we propose some detectable decay channels.Comment: 6 pages, 5 figure

Two-loop Barr-Zee type Contributions to (g−2)μ(g-2)_\mu in the MSSM

We consider the contribution of a two-loop Barr-Zee type diagram to $(g-2)_\mu$ in the minimal supersymmetric standard model (MSSM). At relatively large $\tan\beta$, we show that the contribution of light third generation scalar fermions and neutral CP-even Higgs, $h^0(H^0)$, can easily explain the very recent BNL experimental data. In our analysis $(g-2)_\mu$ prefers negative $A_{f}$ and positive $\mu$. It is more sensitive to the chirality flipping h^0(H^0)\wt{f}_R^*\wt{f}_L rather than chirality conserving couplings.Comment: 10 pages, 5 figures, references adde

AC susceptibility and 51^{51}V NMR study of MnV2_2O4_4

We report $^{51}$V zero-field NMR of manganese vanadate spinel of MnV$_2$O$_4$, together with both ac and dc magnetization measurements. The field and temperature dependence of ac susceptibilities show a reentrant-spin-glass-like behavior below the ferrimagnetic(FEM) ordering temperature. The zero-field NMR spectrum consists of multiple lines ranging from 240 MHz to 320 MHz. Its temperature dependence reveals that the ground state is given by the simultaneous formation of a long-range FEM order and a short-range order component. We attribute the spin-glass-like anomalies to freezing and fluctuations of the short-range ordered state caused by the competition between spin and orbital ordering of the V site

Two inequivalent sublattices and orbital ordering in MnV2O4 studied by 51V NMR

We report detailed 51V NMR spectra in a single crystal of MnV2O4. The vanadium spectrum reveals two peaks in the orbitally ordered state, which arise from different internal hyperfine fields at two different V sublattices. These internal fields evolve smoothly with externally applied field, and show no change in structure that would suggest a change of the orbital ordering. The result is consistent with the orbital ordering model recently proposed by Sarkar et al. [Phys. Rev. Lett. 102, 216405 (2009)] in which the same orbital that is a mixture of t_2g orbitals rotates by about 45$^\circ$ alternately within and between orbital chains in the I4_1/a tetragonal space group.Comment: 4 pages, 4 figures, title changed, published in PRB as a rapid com