On the hyperfine interaction in rare-earth Van Vleck paramagnets at high magnetic fields

An influence of high magnetic fields on hyperfine interaction in the rare-earth ions with non-magnetic ground state (Van Vleck ions) is theoretically investigated for the case of $Tm^{3+}$ ion in axial symmetrical crystal electric field (ethylsulphate crystal). It is shown that magnetic-field induced distortions of $4f$-electron shell lead to essential changes in hyperfine magnetic field at the nucleus. The proposed theoretical model is in agreement with recent experimental data.Comment: 4 pages, no figures, submitted to J. Phys. : Cond. Mat

A geometric interpretation of the spectral parameter for surfaces of constant mean curvature

Considering the kinematics of the moving frame associated with a constant mean curvature surface immersed in S^3 we derive a linear problem with the spectral parameter corresponding to elliptic sinh-Gordon equation. The spectral parameter is related to the radius R of the sphere S^3. The application of the Sym formula to this linear problem yields constant mean curvature surfaces in E^3. Independently, we show that the Sym formula itself can be derived by an appropriate limiting process R -> infinity.Comment: 12 page

Role of the mean curvature in the geometry of magnetic confinement configurations

Examples are presented of how the geometric notion of the mean curvature is used for general magnetic field configurations and magnetic surfaces. It is shown that the mean magnetic curvature is related to the variation of the absolute value of the magnetic field along its lines. Magnetic surfaces of constant mean curvature are optimum for plasma confinement in multimirror open confinement systems and rippled tori.Comment: PDFLaTeX, 10 pages, 5 figure

Temperature dependence of the EPR linewidth of Yb3+ - ions in Y0.99Yb0.01Ba2Cu3OX compounds: Evidence for an anomaly near TC

Electron paramagnetic resonance experiments on doped Yb3+ ions in YBaCuO compounds with different oxygen contents have been made. We have observed the strong temperature dependence of the EPR linewidth in the all investigated samples caused by the Raman processes of spin-lattice relaxation. The spin-lattice relaxation rate anomaly revealed near TC in the superconducting species can be assigned to the phonon density spectrum changesComment: 10 pages, 4 figures Renewed versio

Pseudospherical surfaces on time scales: a geometric definition and the spectral approach

We define and discuss the notion of pseudospherical surfaces in asymptotic coordinates on time scales. Thus we extend well known notions of discrete pseudospherical surfaces and smooth pseudosperical surfaces on more exotic domains (e.g, the Cantor set). In particular, we present a new expression for the discrete Gaussian curvature which turns out to be valid for asymptotic nets on any time scale. We show that asymptotic Chebyshev nets on an arbitrary time scale have constant negative Gaussian curvature. We present also the quaternion-valued spectral problem (the Lax pair) and the Darboux-Backlund transformation for pseudospherical surfaces (in asymptotic coordinates) on arbitrary time scales.Comment: 20 page

書評 八田達夫著 『消費税はやはりいらない』

The superhyperfine structure of the EPR spectra of impurity Nd3+ and U3+ ions in LiYF4, LiLuF4, and LiTmF4 double-fluoride single crystals has been observed and discussed. In LiYF4: Nd (g{pipe} = 1. 987, g⊥ = 2. 554) and LiTmF4: Nd, the superhyperfine structure is observed at the orientation of the external magnetic field B in parallel to the c axis of the crystals and consists of nine components with a splitting of ~15. 4 MHz. In LiYF4: U (g{pipe} = 1. 149, g⊥ = 2. 508) and LiLuF4: U, the superhyperfine structure is observed at both B {pipe} c and B ⊥ c and consists of nine and eleven components, respectively, with a splitting of ~21. 5MHz. It should be noted that the resolution of the superhyperfine structure of the EPR spectrum of LiLuF4: U3+ becomes significantly higher with a deviation from the orientation B ⊥ c. © 2011 Pleiades Publishing, Ltd

Enhanced superhyperfine structure of the EPR spectra of a U3+ ion introduced into the Van Vleck paramagnet LiTmF4

The observation of the superhyperfine structure (SHFS) in EPR spectra due to enhanced nuclear magnetism is reported. The X-band spectrum of a U 3+ ion introduced into the Van Vleck paramagnet LiTmF4 is measured in the temperature range of 5-20 K and compared with the spectra of LiLuF4:U3+ and LiYF4:U3+ single crystals. The spectra reveal well-resolved and strikingly different SHFS. The SHFS of Li(Lu, Y)F4:U3+ is due to the fluorine ions forming the nearest surroundings of the U3+ ion. The main contribution to the SHFS of the U3+ spectrum in LiTmF4 comes from the Tm3+ ions with a highly enhanced nuclear gyromagnetic tensor. © 2008 Pleiades Publishing, Ltd

Superhyperfine structure of the EPR spectra of Nd3+ and U3+ ions in LiRF4 (R = Y, Lu, Tm) double fluorides

The superhyperfine structure of the EPR spectra of impurity Nd3+ and U3+ ions in LiYF4, LiLuF4, and LiTmF4 double-fluoride single crystals has been observed and discussed. In LiYF4: Nd (g{pipe} = 1. 987, g⊥ = 2. 554) and LiTmF4: Nd, the superhyperfine structure is observed at the orientation of the external magnetic field B in parallel to the c axis of the crystals and consists of nine components with a splitting of ~15. 4 MHz. In LiYF4: U (g{pipe} = 1. 149, g⊥ = 2. 508) and LiLuF4: U, the superhyperfine structure is observed at both B {pipe} c and B ⊥ c and consists of nine and eleven components, respectively, with a splitting of ~21. 5MHz. It should be noted that the resolution of the superhyperfine structure of the EPR spectrum of LiLuF4: U3+ becomes significantly higher with a deviation from the orientation B ⊥ c. © 2011 Pleiades Publishing, Ltd

Stabilization of test particles in Induced Matter Kaluza-Klein theory

The stability conditions for the motion of classical test particles in an $n$-dimensional Induced Matter Kaluza-Klein theory is studied. We show that stabilization requires a variance of the strong energy condition for the induced matter to hold and that it is related to the hierarchy problem. Stabilization of test particles in a FRW universe is also discussed.Comment: 15 pages, 1 figure, to appear in Class. Quantum Gra

Theory of AC Josepson Effect in Superconducting Constrictions

We have developed a microscopic theory of ac Josephson effect in short ballistic superconducting constrictions with arbitrary electron transparency and in constrictions with diffusive electron transport. The theory is valid for arbitrary miscroscopic structure of the superconducting electrodes of the constriction. As applications of the theory we study smearing of the subgap current singularities by pair-breaking effects and also the structure of these singularities in the constrictions between the composite S/N electrodes with the proximity-induced gap in the normal layer.Comment: 11 pages, RevTex, 3 figures available on reques