The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Hari Dahal - One of the best experts on this subject based on the ideXlab platform.
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spin waves in quasiequilibrium spin Systems
Physical Review Letters, 2006Co-Authors: Kevin S Bedell, Hari DahalAbstract:Using the Landau Fermi liquid theory we discovered a new propagating transverse spin wave in a Paramagnetic System which is driven slightly out of equilibrium without applying an external magnetic field. We find a gapless mode which describes the uniform precession of the magnetization in the absence of a magnetic field. We also find a gapped mode associated with the precession of the spin current around the internal field. The gapless mode has a quadratic dispersion leading to a T{sup 3/2} contribution to the specific heat. These modes significantly contribute to the dynamic structure function.
Matthew P A Fisher - One of the best experts on this subject based on the ideXlab platform.
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graphene integer quantum hall effect in the ferromagnetic and Paramagnetic regimes
Physical Review B, 2006Co-Authors: Jason Alicea, Matthew P A FisherAbstract:Starting from the graphene lattice tight-binding Hamiltonian with an on-site $U$ and long-range Coulomb repulsion, we derive an interacting continuum Dirac theory governing the low-energy behavior of graphene in an applied magnetic field. Initially, we consider a clean graphene System within this effective theory and explore integer quantum Hall ferromagnetism stabilized by exchange from the long-range Coulomb repulsion. We study in detail the ground state and excitations at $\ensuremath{\nu}=0$ and $\ensuremath{\nu}=\ifmmode\pm\else\textpm\fi{}1$, taking into account small symmetry-breaking terms that arise from the lattice-scale interactions, and also explore the ground states selected at $\ensuremath{\nu}=\ifmmode\pm\else\textpm\fi{}3$, $\ifmmode\pm\else\textpm\fi{}4$, and $\ifmmode\pm\else\textpm\fi{}5$. We argue that the ferromagnetic regime may not yet be realized in current experimental samples, which at the above filling factors perhaps remain Paramagnetic due to strong disorder. In an attempt to access the latter regime where the role of exchange is strongly suppressed by disorder, we apply Hartree theory to study the effects of interactions. Here, we find that Zeeman splitting together with symmetry-breaking interactions can in principle produce integer quantum Hall states in a Paramagnetic System at $\ensuremath{\nu}=0$, $\ifmmode\pm\else\textpm\fi{}1$, and $\ifmmode\pm\else\textpm\fi{}4$, but not at $\ensuremath{\nu}=\ifmmode\pm\else\textpm\fi{}3$ or $\ifmmode\pm\else\textpm\fi{}5$, consistent with recent experiments in high magnetic fields. We make predictions for the activation energies in these quantum Hall states which will be useful for determining their true origin.
P Schiffer - One of the best experts on this subject based on the ideXlab platform.
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slow spin relaxation in a highly polarized cooperative paramagnet
Physical Review Letters, 2006Co-Authors: B G Ueland, G C Lau, R J Cava, James R Obrien, P SchifferAbstract:We report measurements of the ac susceptibility of the cooperative paramagnet ${\mathrm{Tb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ in a strong magnetic field. Our data show the expected saturation maximum in $\ensuremath{\chi}(T)$ and also an unexpected frequency dependence of this peak at low frequencies ($l1\text{ }\text{ }\mathrm{Hz}$), suggesting very slow spin relaxations are occurring. Measurements on samples diluted with nonmagnetic ${\mathrm{Y}}^{3+}$ or ${\mathrm{Lu}}^{3+}$ and complementary measurements on pure and diluted ${\mathrm{Dy}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ strongly suggest that the relaxation is associated with dipolar spin correlations, representing unusual cooperative behavior in a Paramagnetic System.
Drahomir Hnyk - One of the best experts on this subject based on the ideXlab platform.
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the behavior of a Paramagnetic System in electric and magnetic fields as exemplified by revisiting li b10h14
Physical Chemistry Chemical Physics, 2017Co-Authors: Miroslav Medved, Taye B Demissie, Michael L Mckee, Drahomir HnykAbstract:The electric and magnetic properties of the Li@B10H14 complex, considered as a novel inorganic electride-type System with potential for second-order non-linear optical (NLO) applications, have already been studied. However, the reported C2v structure is not the global energy minimum and therefore its electronic and magnetic properties need to be revisited. Moreover, by applying more accurate computational protocols (ROHF-CCSD/CCSD(T) and larger basis sets) we show that the model chemistry used earlier (UMP2/6-31+G(d)) is not sufficient for reliable description of the NLO responses of this open-shell doublet complex. The global minimum based on the Cs symmetry is significantly (by ca. 25 kcal mol−1) more stable than the C2v structure and it should be viewed as a System with moderate NLO responses. An excess of unpaired electron density is also responsible for the contact and pseudo-contact contributions to the magnetic properties, which was not considered in the earlier work.
Junichi Yamada - One of the best experts on this subject based on the ideXlab platform.
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new family of six stable metals with a nearly isotropic triangular lattice of organic radical cations and diluted Paramagnetic System of anions κ κ bdh ttp 4mx4 solv where m coii mnii x cl br and solv h2o 5 ch2x2
Crystal Growth & Design, 2016Co-Authors: Andrey A Bardin, Hiroki Akutsu, Junichi YamadaAbstract:A new family of six Paramagnetic metals, namely, κ-(BDH-TTP)4CoCl4·(H2O)5 (I), κ-(BDH-TTP)4Co0.54Mn0.46Cl4·(H2O)5 (II), κ-(BDH-TTP)4MnCl4·(H2O)5 (III), κ⊥-(BDH-TTP)4CoBr4·(CH2Cl2) (IV), κ⊥-(BDH-TTP)4MnBr4·(CH2Cl2) (V), and κ⊥-(BDH-TTP)4MnBr4·(CH2Br2) (VI), has been synthesized and characterized by X-ray crystallography, four-probe conductivity measurements, SQUID magnetometry, and calculations of electronic structure. The newly discovered κ⊥-type packing motif of organic layers differs from the parent κ-type by a series of longitudinal shifts of BDH-TTP radical cations in the crystal structure. Salts I–VI form two isostructural groups: I–III (κ) and IV–VI (κ⊥). Salts I–III are isostructural to the previously discovered κ-(BDH-TTP)2FeIIIX4 (X = Cl, Br) even though the charge of FeX4– anions is half that of the MX42– (M = Co, Mn) anions. The tetrahedral anions are disordered in I–III but completely ordered in IV–VI. The type of included solvent molecule is solely determined by the anion size. The paramagnet...
