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The valence electron Compton profile of trigonal and polycrystalline trigonal selenium has been determined using the self-consistent OPW method. The anisotropy of the Compton profile between directions parallel and perpendicular to the c-axis is discussed. The results are compared with experimental data. The difference of the Compton profiles of the amorphous and polycrystalline phases is examined. 相似文献
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The specific heats of the Rare Earth metals Eu and Er have been measured in the temperature range 0.03 to 0.8K. The measurements yield magnetic hyperfine parameters of 13.2 mK, 5.85 mK, and 42.3 mK for 151Eu, 153Eu, and 167Er, respectively, corresponding to magnetic hyperfine fields of 0.26 and 7.2 MOe for Eu and Er. The nuclear quadrupole coupling constants were found to be ?0.06 mK, ?0.16 mK, and ?2.7 mK for 151Eu, 153Eu and 167Er. 相似文献
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V.B. Eltsov R. HänninenM. Krusius 《Physica C: Superconductivity and its Applications》2010,470(19):803-808
Rapidly evolving non-equilibrium phenomena, associated with phase transitions from meta-stable states, provide examples of most complex dynamics. Condensed matter many-particle quantum systems, which are described in terms of a coherent quantum field, are a particularly useful environment for such studies. Among them, the 3He superfluids display the largest variety of topological defects of different dimensionality and structure, owing to the large degree of freedom in the rearrangement of their multi-component p-wave order parameter field. A few measurements exist which monitor the non-equilibrium phase transition dynamics and display defect formation. 相似文献
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Autti S Bunkov YM Eltsov VB Heikkinen PJ Hosio JJ Hunger P Krusius M Volovik GE 《Physical review letters》2012,108(14):145303
Long-lived coherent spin precession of (3)He-B at low temperatures around 0.2T(c) is a manifestation of Bose-Einstein condensation of spin-wave excitations or magnons in a magnetic trap which is formed by the order-parameter texture and can be manipulated experimentally. When the number of magnons increases, the orbital texture reorients under the influence of the spin-orbit interaction and the profile of the trap gradually changes from harmonic to a square well, with walls almost impenetrable to magnons. This is the first experimental example of Bose condensation in a box. By selective rf pumping the trap can be populated with a ground-state condensate or one at any of the excited energy levels. In the latter case the ground state is simultaneously populated by relaxation from the exited level, forming a system of two coexisting condensates. 相似文献
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Finne AP Eltsov VB Eska G Hänninen R Kopu J Krusius M Thuneberg EV Tsubota M 《Physical review letters》2006,96(8):085301
A surface-mediated process is identified in 3He-B which generates vortices at a roughly constant rate. It precedes a faster form of turbulence where intervortex interactions dominate. This precursor becomes observable when vortex loops are introduced in low-velocity rotating flow at sufficiently low mutual friction dissipation at temperatures below 0.5Tc. Our measurements indicate that the formation of new loops is associated with a single vortex interacting in the applied flow with the sample boundary. Numerical calculations show that the single-vortex instability arises when a helical Kelvin wave expands from a reconnection kink at the wall and then intersects again with the wall. 相似文献
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Hosio JJ Eltsov VB de Graaf R Heikkinen PJ Hänninen R Krusius M L'vov VS Volovik GE 《Physical review letters》2011,107(13):135302
Steady-state turbulent motion is created in superfluid (3)He-B at low temperatures in the form of a turbulent vortex front, which moves axially along a rotating cylindrical container of (3)He-B and replaces vortex-free flow with vortex lines at constant density. We present the first measurements on the thermal signal from dissipation as a function of time, recorded at 0.2T(c) during the front motion, which is monitored using NMR techniques. Both the measurements and the numerical calculations of the vortex dynamics show that at low temperatures the density of the propagating vortices falls well below the equilibrium value, i.e., the superfluid rotates at a smaller angular velocity than the container. This is the first evidence for the decoupling of the superfluid from the container reference frame in the zero-temperature limit. 相似文献
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A review of the nonrelativistic self-consistent symmertrized orthogonalized-plane-wave (SCSOPW ) method used for determining electronic energy bands in periodic solids is given. Working equations based on the full use of group theory at all stages are presented for elemental crystals. As an example the method is applied to the trigonal selenium crystal. 相似文献