534 research outputs found
Low temperature electronic properties of Sr_2RuO_4 III: Magnetic fields
Based on the microscopic model introduced previously the observed specific
heat and ac-susceptibility data in the superconducting phase in Sr_2RuO_4 with
applied magnetic fields are described consistently within a phenomenological
approach. Discussed in detail are the temperature dependence of the upper
critical fields H_{c2} and H_2, the dependence of the upper critical fields on
the field direction, the linear specific heat below the superconducting phase
transition as a function of field or temperature, the anisotropy of the two
spatial components of the order parameter, and the fluctuation field H_p.Comment: 8 pages REVTEX, 4 figure
Quasiclassical Limit in q-Deformed Systems, Noncommutativity and the q-Path Integral
Different analogs of quasiclassical limit for a q-oscillator which result in
different (commutative and non-commutative) algebras of ``classical''
observables are derived. In particular, this gives the q-deformed Poisson
brackets in terms of variables on the quantum planes. We consider the
Hamiltonian made of special combination of operators (the analog of even
operators in Grassmann algebra) and discuss q-path integrals constructed with
the help of contracted ``classical'' algebras.Comment: 19 pages, Late
Financial sector and economic growth in the Republic of Croatia 1995-2005
Financial sector in the Republic of Croatia had a strong growth between 1995 2005.g. Liberalization of financial sector in 1999 led to an increase in bank foreign debt, which resulted in a strong increase in foreign currency reserves and appreciation of the national currency. The growth of the financial sector and credit expansion have been allocated in favour of private and public consumption, but not in industry investments. GDP growth didn't have the same momentum as financial aggregates. Economic growth, after a contraction in 1999 was within the average of global economic growth. Relying on neoclassical growth model, government and central bank didn't put in place the needed set of pro-active policies. Factor allocation was solely through private bank channels financing private consumption. If the sustainable economic growth and new employment are to be major macroeconomic goals, a new macroeconomic paradigm as combination of neclassical and neokeynesians approach will be needed
Low temperature electronic properties of Sr_2RuO_4 I: Microscopic model and normal state properties
Starting from the quasi one-dimensional kinetic energy of the d_{yz} and
d_{zx} bands we derive a bosonized description of the correlated electron
system in Sr_2RuO_4. At intermediate coupling the magnetic correlations have a
quasi one-dimensional component along the diagonals of the basal plane of the
tetragonal unit cell that accounts for the observed neutron scattering results.
Together with two-dimensional correlations the model consistently accounts for
the normal phase specific heat, cyclotron mass enhancement, static
susceptibility, and Wilson ratio and implies an anomalous high temperature
resistivity.Comment: 12 pages REVTEX, 6 figure
Low temperature electronic properties of Sr_2RuO_4 II: Superconductivity
The body centered tetragonal structure of Sr_2RuO_4 gives rise to umklapp
scattering enhanced inter-plane pair correlations in the d_{yz} and d_{zx}
orbitals. Based on symmetry arguments, Hund's rule coupling, and a bosonized
description of the in-plane electron correlations the superconducting order
parameter is found to be a orbital-singlet spin-triplet with two spatial
components. The spatial anisotropy is 7%. The different components of the order
parameter give rise to two-dimensional gapless fluctuations. The phase
transition is of third order. The temperature dependence of the pair density,
specific heat, NQR, Knight shift, and susceptibility are in agreement with
experimental results.Comment: 20 pages REVTEX, 3 figure
Dynamics of Entanglement in One-Dimensional Spin Systems
We study the dynamics of quantum correlations in a class of exactly solvable
Ising-type models. We analyze in particular the time evolution of initial Bell
states created in a fully polarized background and on the ground state. We find
that the pairwise entanglement propagates with a velocity proportional to the
reduced interaction for all the four Bell states. Singlet-like states are
favored during the propagation, in the sense that triplet-like states change
their character during the propagation under certain circumstances.
Characteristic for the anisotropic models is the instantaneous creation of
pairwise entanglement from a fully polarized state; furthermore, the
propagation of pairwise entanglement is suppressed in favor of a creation of
different types of entanglement. The ``entanglement wave'' evolving from a Bell
state on the ground state turns out to be very localized in space-time. Further
support to a recently formulated conjecture on entanglement sharing is given.Comment: 25 pages, 21 figures; revte
Material-Specific Investigations of Correlated Electron Systems
We present the results of numerical studies for selected materials with
strongly correlated electrons using a combination of the local-density
approximation and dynamical mean-field theory (DMFT). For the solution of the
DMFT equations a continuous-time quantum Monte-Carlo algorithm was employed.
All simulations were performed on the supercomputer HLRB II at the Leibniz
Rechenzentrum in Munich. Specifically we have analyzed the pressure induced
metal-insulator transitions in Fe2O3 and NiS2, the charge susceptibility of the
fluctuating-valence elemental metal Yb, and the spectral properties of a
covalent band-insulator model which includes local electronic correlations.Comment: 14 pages, 7 figures, to appear in "High Performance Computing in
Science and Engineering, Garching 2009" (Springer
Rechtvaardigheid in klimaatbeleid:Over de verdeling van klimaatkosten
We zijn op een nieuw punt aanbeland in het debat over klimaatbeleid. Ooit ging het over de vraag of de aarde daadwerkelijk opwarmt door menselijk toedoen. Vervolgens ging het over de vraag wat daaraan te doen valt. Nu gaat het steeds vaker over de vraag wie de kosten van klimaatmaatregelen en van klimaatschademoet betalen. De protesten van de ‘gele hesjes’ in Frankrijk hebben laten zien hoe belangrijk het is dat de verdeling van zulke klimaatkosten als rechtvaardig gezien wordt. Als dat niet het geval is, dan kan het draagvlak voor klimaatbeleid afkalven. Hoe kunnen rechtvaardige verdelingen eruit zien? Dat analyseert de Wetenschappelijke Raad voor het Regeringsbeleid (wrr) in dit rapport. De hoofdboodschap van dit rapport is dat er in klimaatbeleid stelselmatige aandacht moet zijn voor de rechtvaardigheid van verdelingen. Maatregelen dienen niet alleen beoordeeld te worden vanuit het perspectief van doelmatigheid en rechtmatigheid, maar ook vanuit het perspectief van rechtvaardigheid. Onze belangrijkste boodschap is daarom dat de mogelijke verdelingen van klimaatkosten al vooraf expliciet op tafel komen en worden doordacht. Dat helptbeleidsmakers om meer oog te krijgen voor mogelijke onbedoelde en ongewensteneveneffecten. Het leidt ook tot een meer afgewogen en transparanter politiek debat. En het zorgt ervoor dat het draagvlak voor klimaatbeleid op peil blijft. De wrr doet drie aanbevelingen hoe de overheid rechtvaardige verdelingen in het klimaatbeleid tot stand kan brengen: zorg voor (1) inhoudelijke verbreding, (2) procedurele verankering en (3) institutionele borging
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