排序方式: 共有35条查询结果,搜索用时 609 毫秒
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Ballou S Goodpaster J MacCrehan W Reeder D 《Analytical and bioanalytical chemistry》2003,376(8):1149-1150
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Loire M Simonet V Petit S Marty K Bordet P Lejay P Ollivier J Enderle M Steffens P Ressouche E Zorko A Ballou R 《Physical review letters》2011,106(20):207201
The spin-wave excitations emerging from the chiral helically modulated 120° magnetic order in a langasite Ba?NbFe?Si?O?? enantiopure crystal were investigated by unpolarized and polarized inelastic neutron scattering. A dynamical fingerprint of the chiral ground state is obtained, singularized by (i) spectral weight asymmetries answerable to the structural chirality and (ii) a full chirality of the spin correlations observed over the whole energy spectrum. The intrinsic chiral nature of the spin waves' elementary excitations is shown in the absence of macroscopic time-reversal symmetry breaking. 相似文献
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Zorko A Pregelj M Potočnik A van Tol J Ozarowski A Simonet V Lejay P Petit S Ballou R 《Physical review letters》2011,107(25):257203
We present an electron spin resonance (ESR) investigation of the acentric Ba(3)NbFe(3)Si(2)O(14), featuring a unique single-domain double-chiral magnetic ground state. Combining simulations of the ESR linewidth anisotropy and the antiferromagnetic-resonance modes allows us to single out the Dzyaloshinsky-Moriya (DM) interaction as the leading magnetic anisotropy term. We demonstrate that the rather minute out-of-plane DM component d(c)=45 mK is responsible for selecting a unique ground state, which endures thermal fluctuations up to astonishingly high temperatures. 相似文献
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We investigate the classical spin dynamics of the kagome antiferromagnet by combining Monte Carlo and spin dynamics simulations. We show that this model has two distinct low temperature dynamical regimes, both sustaining propagative modes. The expected gauge invariance type of the low energy, low temperature, out-of-plane excitations is also evidenced in the nonlinear regime. A detailed analysis of the excitations allows us to identify ghosts in the dynamical structure factor, i.e., propagating excitations with a strongly reduced spectral weight. We argue that these dynamical extinction rules are of geometrical origin. 相似文献
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Brando M Duncan WJ Moroni-Klementowicz D Albrecht C Grüner D Ballou R Grosche FM 《Physical review letters》2008,101(2):026401
The d-electron low temperature magnet NbFe2 is poised near the threshold of magnetism at ambient pressure, and can be tuned across the associated quantum critical point by adjusting the precise stoichiometry within the Nb1-yFe2+y homogeneity range. In a nearly critical single crystal (y= -0.01), we observe a T3/2 power-law dependence of the resistivity rho on temperature T and a logarithmic temperature dependence of the Sommerfeld coefficient gamma=C/T of the specific heat capacity C over nearly 2 orders of magnitude in temperature, extending down to 0.1 K. 相似文献
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G.M. Kalvius E. Schreier M. Ekström O. Hartmann S. Henneberger A. Kratzer R. Wäppling E. Martin F.J. Burghart R. Ballou J. Deportes Ch. Niedermayer 《Hyperfine Interactions》2000,128(1-3):275-303
After a short introduction to μSR with respect to the study of magnetic properties, followed by a brief outline of the principle
of the high pressure-low temperature μSR spectrometer installed at the Paul Scherrer Institute, we discuss some measurements
on rare earth materials employing this instrument. They are concerned with: (1) The pressure dependence of the spin turning
process in ferromagnetic Gd. (2) The volume dependence of the internal magnetic field in the heavy rare earth metals Gd, Dy,
and Ho in their ordered magnetic states. (3) The response of the (first order) magnetic transition in the frustrated antiferromagnets
of type RMn2 (R = Y,Gd) to pressure. (4) The variation of magnetic parameters with pressure in La2CuO4 (powder sample), the antiferromagnetic parent compound of the high TC superconductors of type La2−x(Sr, Ba)xCuO4. In conclusion a short outlook on further developments is given.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Donald P. Ballou 《Archive for Rational Mechanics and Analysis》1974,56(2):170-182
In the study of weak solutions to nonlinear hyperbolic partial differential equations both rarefaction waves and compression waves arise. Although the behavior of rarefaction waves is known for all time, the characteristics that determine a compression wave intersect and hence the development of the wave is not easily determined. The purpose of this paper is to study compression waves. As a first step we consider the Cauchy problem for the nonlinear wave equation. We show that if the data outside some finite interval consist of constant states, then after finite time the solution involves the same states as does the solution to the Riemann problem determined by these constant states. This result is then applied to compression waves to obtain information on the shock that arises and on the steady-state solution. The region of interaction is also described. This information is obtained via a constructive procedure. 相似文献