232 research outputs found
Unusual giant magnetostriction in the ferrimagnet GdCaMnO
We report an unusual giant linear magnetostrictive effect in the ferrimagnet
GdCaMnO (80 K). Remarkably, the
magnetostriction, negative at high temperature (), becomes
positive below 15 K when the magnetization of the Gd sublattice overcomes the
magnetization of the Mn sublattice. A rather simple model where the magnetic
energy competes against the elastic energy gives a good account of the observed
results and confirms that Gd plays a crucial role in this unusual observation.
Unlike previous works in manganites where only striction associated with 3
Mn orbitals is considered, our results show that the lanthanide 4 orbitals
related striction can be very important too and it cannot be disregarded.Comment: 6 pages, 3 figure
Heat capacity studies of Ce and Rh site substitution in the heavy fermion antiferromagnet CeRhIn_5;: Short-range magnetic interactions and non-Fermi-liquid behavior
In heavy fermion materials superconductivity tends to appear when long range
magnetic order is suppressed by chemical doping or applying pressure. Here we
report heat capacity measurements on diluted alloyes of the heavy fermion
superconductor CeRhIn_5;. Heat capacity measurements have been performed on
CeRh_{1-y}Ir_{y}In_5; (y <= 0.10) and Ce_{1-x}La_{x}Rh_{1-y}Ir_{y}In_5; (x <=
0.50) in applied fields up to 90 kOe to study the affect of doping and magnetic
field on the magnetic ground state. The magnetic phase diagram of
CeRh_{0.9}Ir_{0.1}In_5; is consistent with the magnetic structure of CeRhIn_5;
being unchanged by Ir doping. Doping of Ir in small concentrations is shown to
slightly increase the antiferromagnetic transition temperature T_{N} (T_{N}=3.8
K in the undoped sample). La doping which causes disorder on the Ce sublattice
is shown to lower T_{N} with no long range order observed above 0.34 K for
Ce_{0.50}La_{0.50}RhIn_5;. Measurements on Ce_{0.50}La_{0.50}RhIn_5; show a
coexistence of short range magnetic order and non-Fermi-liquid behavior. This
dual nature of the Ce 4f-electrons is very similar to the observed results on
CeRhIn_5; when long range magnetic order is suppressed at high pressure.Comment: 8 pages, 9 figure
Magnetic Structure Of Cerhin5 As A Function Of Pressure And Temperature
We report magnetic neutron-diffraction and electrical resistivity studies on single crystals of the heavy-fermion antiferromagnet CeRhIn5 at pressures up to 2.3 GPa. These experiments show that the staggered moment of Ce and the incommensurate magnetic structure change weakly with applied pressure up to 1.63 GPa, where resistivity, specific heat and nuclear quadrupole resonance measurements confirm the presence of bulk superconductivity. This work places important constraints on an interpretation of the relationship between antiferromagnetism and unconventional superconductivity in CeRhIn 5.692244031244036Heffner, R.H., Norman, M.R., (1996) Comments Condens. Matter Phys., 17, p. 361Stewart, G.R., (2001) Rev. Mod. Phys., 73, p. 797Mathur, N.D., Grosche, F.M., Julian, S.R., Walker, I.R., Freye, D.M., Haselwimmer, R.K.W., Lonzarich, G.G., (1998) Nature (London), 394, p. 39Sato, N.K., Aso, N., Miyake, K., Shiina, R., Thalmeier, P., Varelogiannis, G., Geibel, C., Komatsubara, T., (2001) Nature (London), 410, p. 340Fisk, Z., Ott, H.R., Smith, J.L., (1986) Proceedings of the Sixth Annual Conference, , Los Alamos, NM, USA, (unpublished)Fisk, Z., Hess, D.W., Pethick, C.J., Pines, D., Smith, J.L., Thompson, J.D., Willis, J.O., (1988) Science, 239, p. 4835Miyake, K., Schmitt-Rink, S., Varma, C.M., (1986) Phys. Rev. B, 34, p. 6554Monthoux, P., Balatsky, A.V., Pines, D., (1991) Phys. Rev. Lett., 67, p. 3448Coleman, P., Pepin, C., (2002) Physica B, 312-313, p. 383Walker, I.R., Grosche, F.M., Freye, D.M., Lonzarich, G.G., (1997) Physica C, 282-287, p. 303Morin, P., Vettier, C., Flouquet, J., Konczykowski, M., Lassailly, Y., Mignot, J.M., Welp, U., (1988) J. Low Temp. Phys., 70, p. 377Jaccard, D., Wilhelm, H., Alami-Yadri, K., Vargoz, E., (1999) Physica B, 259-261, p. 1Jaccard, D., Behnia, K., Sierro, J., (1992) Phys. Lett. A, 163, p. 475Thompson, J.D., Parks, R.D., Borges, H., (1986) J. Magn. Magn. Mater., 54-57, p. 377Grosche, F.M., Julian, S.R., Mathur, N.D., Lonzarich, G.G., (1996) Physica B, 223-224, p. 50Movshovich, R., Graf, T., Mandrus, D., Thompson, J.D., Smith, J.L., Fisk, Z., (1996) Phys. Rev. B, 53, p. 8241Petrovic, C., Moshopoulou, E.G., Hundley, M.F., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2000) Phys. Rev. Lett., 84, p. 4986Petrovic, C., Movshovich, R., Jaime, M., Pagliuso, P.G., Hundley, M.F., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2001) Europhys. Lett., 53, p. 354Petrovic, C., Pagliuso, P.G., Hundley, M.F., Movshovich, R., Sarrao, J.L., Thompson, J.D., Fisk, Z., Monthoux, P., (2001) J. Phys.: Condens. Matter, 13, pp. L337Zheng, G.-Q., Tanabe, K., Mito, T., Kawasaki, S., Kitaoka, Y., Aoki, D., Haga, Y., Onuki, Y., (2001) Phys. Rev. Lett., 86, p. 4664Movshovich, R., Jaime, M., Thompson, J.D., Petrovic, C., Fisk, Z., Pagliuso, P.G., Sarrao, J.L., (2001) Phys. Rev. Lett., 86, p. 5152Fisher, R.A., Bouquet, F., Phillips, N.E., Hundley, M.F., Pagliuso, P.G., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2002) Phys. Rev. B, 65, p. 224509Kawasaki, S., Mito, T., Kawasaki, Y., Zheng, G.-Q., Kitaoka, Y., Aoki, D., Haga, Y., Onuki, Y., cond-mat/0303123 (unpublished)Mito, T., Kawasaki, S., Zheng, G.-Q., Kawasaki, Y., Ishida, K., Kitaoka, Y., Aoki, D., Onuki, Y., (2001) Phys. Rev. B, 63, p. 220507Mito, T., Kawasaki, S., Zheng, G.-Q., Kawasaki, Y., Ishida, K., Kitaoka, Y., Aoki, D., Onuki, Y., (2002) Physica B, 312-313, p. 16Izawa, K., Yamaguchi, H., Matsuda, Y., Shishido, H., Settai, R., Onuki, Y., (2001) Phys. Rev. Lett., 87, p. 057002Pagliuso, P.G., Petrovic, C., Movshovich, R., Hall, D., Hundley, M.F., Sarrao, J.L., Thompson, J.D., Fisk, Z., (2001) Phys. Rev. B, 64, p. 100503Zapf, V.S., Freeman, E.J., Bauer, E.D., Petricka, J., Sirvent, C., Frederick, N.A., Dickey, R.P., Maple, M.B., (2002) Phys. Rev. B, 65, p. 014506Moshopoulou, E.G., Fisk, Z., Sarrao, J.L., Thompson, J.D., (2001) J. Solid State Chem., 158, p. 25Curro, N.J., Hammel, P.C., Pagliuso, P.G., Sarrao, J.L., Thompson, J.D., Fisk, Z., (2000) Phys. Rev. B, 62, pp. R6100Bao, W., Pagliuso, P.G., Sarrao, J.L., Thompson, J.D., Fisk, Z., Lynn, J.W., Erwin, R.W., (2000) Phys. Rev. B, 62, p. 14621(2003) Phys. Rev. B, 67, pp. 099903EMito, T., Kawasaki, S., Kawasaki, Y., Zheng, G.-Q., Kitaoka, Y., Aoki, D., Haga, Y., Onuki, Y., (2003) Phys. Rev. Lett., 90, p. 077004Bao, W., Trevino, S.F., Lynn, J.W., Pagliuso, P.G., Sarrao, J.L., Thompson, J.D., Fisk, Z., (2002) Appl. Phys. A Mater. Sci. Process. A, 74, p. 557Majumdar, S., Balakrishnan, G., Lees, M.R., Paul, D.McK., McIntyre, G.J., (2002) Phys. Rev. B, 66, p. 212502Kawasaki, S., (2002) Phys. Rev. B, 65, p. 020504Shishido, H., Settai, R., Araki, S., Ueda, T., Inada, Y., Kobayashi, T.C., Muramatsu, T., Onuki, Y., (2002) Phys. Rev. B, 66, p. 214510Kumar, R.S., Kohlmonn, H., Light, B.E., Cornelius, A.L., Raghavan, V., Darling, T.W., Sarrao, J.L., cond-mat/0209005 (unpublished)Moshopoulou, E.G., Fisk, Z., Sarrao, J.L., Thompson, J.D., (2001) J. Solid State Chem., 25, p. 158Pagliuso, P.G., Petrovic, C., Movshovich, R., Hall, D., Hundley, M.F., Sarrao, J.L., Thompson, J.D., Fisk, Z., (2001) Phys. Rev. B, 64, p. 100503Thompson, J.D., (1984) Rev. Sci. Instrum., 55, p. 231Bao, W., Aeppli, G., Lynn, J.W., Pagliuso, P.G., Sarrao, J.L., Hundley, M.F., Thompson, J.D., Fisk, Z., (2002) Phys. Rev. B, 65, p. 100505Cooper, M.J., (1968) Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr., A6, p. 624Cooper, M.J., Nathans, R., (1968) Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr., A6, p. 619Mignot, J.-M., Bourdarot, F., Llobet, A., Abanov, Ar., private communicationBlume, M., Freeman, A.J., Watson, R.E., (1962) J. Chem. Phys., 37, p. 1245Christianson, A.D., Lawrence, J.M., Pagliuso, R.G., Moreno, N.O., Sarrao, J.L., Thompson, J.D., Riseborough, P.S., Lacerda, A.H., (2002) Phys. Rev. B, 66, p. 193102Curro, N.J., Sarrao, J.L., Thompson, J.D., Pagliuso, P.G., Kos, S., Abanov, Ar., Pines, D., (2003) Phys. Rev. Lett., 90, p. 227202Knebel, G., Braithwaite, D., Canfield, P.C., Lapertot, G., Flouquet, J., (2002) High Press. Res., 22, p. 16
Localized f electrons in CexLa1-xRhIn5: dHvA Measurements
Measurements of the de Haas-van Alphen effect in CexLa1-xRhIn5 reveal that
the Ce 4f electrons remain localized for all x, with the mass enhancement and
progressive loss of one spin from the de Haas-van Alphen signal resulting from
spin fluctuation effects. This behavior may be typical of antiferromagnetic
heavy fermion compounds, inspite of the fact that the 4f electron localization
in CeRhIn5 is driven, in part, by a spin-density wave instability.Comment: 4 pages, 4 figures, submitted to PR
Formation of superdense hadronic matter in high energy heavy-ion collisions
We present the detail of a newly developed relativistic transport model (ART
1.0) for high energy heavy-ion collisions. Using this model, we first study the
general collision dynamics between heavy ions at the AGS energies. We then show
that in central collisions there exists a large volume of sufficiently
long-lived superdense hadronic matter whose local baryon and energy densities
exceed the critical densities for the hadronic matter to quark-gluon plasma
transition. The size and lifetime of this matter are found to depend strongly
on the equation of state. We also investigate the degree and time scale of
thermalization as well as the radial flow during the expansion of the
superdense hadronic matter. The flow velocity profile and the temperature of
the hadronic matter at freeze-out are extracted. The transverse momentum and
rapidity distributions of protons, pions and kaons calculated with and without
the mean field are compared with each other and also with the preliminary data
from the E866/E802 collaboration to search for experimental observables that
are sensitive to the equation of state. It is found that these inclusive,
single particle observables depend weakly on the equation of state. The
difference between results obtained with and without the nuclear mean field is
only about 20\%. The baryon transverse collective flow in the reaction plane is
also analyzed. It is shown that both the flow parameter and the strength of the
``bounce-off'' effect are very sensitive to the equation of state. In
particular, a soft equation of state with a compressibility of 200 MeV results
in an increase of the flow parameter by a factor of 2.5 compared to the cascade
case without the mean field. This large effect makes it possible to distinguish
the predictions from different theoretical models and to detect the signaturesComment: 55 pages, latex, + 39 figures available upon reques
Dependence of crystalline, ferroelectric and fracture toughness on annealing in Pb(Zr0.52Ti0.48)O3 thin films deposited by metal organic decomposition
Characterization of Avian Influenza Viruses A (H5N1) from Wild Birds, Hong Kong, 2004–2008
Repeated detection of subclade 2.3.2 viruses in nonpasserine birds from different regions suggests possible establishment of this lineage in wild bird species
Metastability Driven by Soft Quantum Fluctuation Modes
The semiclassical Euclidean path integral method is applied to compute the
low temperature quantum decay rate for a particle placed in the metastable
minimum of a cubic potential in a {\it finite} time theory. The classical path,
which makes a saddle for the action, is derived in terms of Jacobian elliptic
functions whose periodicity establishes the one-to-one correspondence between
energy of the classical motion and temperature (inverse imaginary time) of the
system. The quantum fluctuation contribution has been computed through the
theory of the functional determinants for periodic boundary conditions. The
decay rate shows a peculiar temperature dependence mainly due to the softening
of the low lying quantum fluctuation eigenvalues. The latter are determined by
solving the Lam\`{e} equation which governs the fluctuation spectrum around the
time dependent classical bounce.Comment: Journal of Low Temperature Physics (2008) Publisher: Springer
Netherland
Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications.
BACKGROUND: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea.
METHOD: The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea.
CONCLUSIONS: The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy.(undefined)info:eu-repo/semantics/publishedVersio
- …