262,189 research outputs found
Critical properties of a magnetized Bose gas
No full text The critical behaviour of a dilute spin-S Bose gas in a magnetic field is investigated with the help of the renormalization group method. A complete set of critical exponents is given both at constant pressure and constant density. The magnetic properties are also discussed. </jats:p
Dome-shaped phase diagram in the spin-1 XY ferromagnet with biquadratic exchange and longitudinal easy-axis crystal field
No full textWe investigate the phase diagram of a spin-1 ferromagnetic XY model in the presence of a longitudinal easy-axis crystal field assuming bilinear (J) and biquadratic (I) exchange interactions between nearest neighbors spins and using the two-time Green Functions framework at the level of the Devlin strategy. Employing both analytical estimates and numerical calculations, we find that the structure of the crystal-field-induced phase boundary changes sensibly as the ratio α=I/J increases. In particular, when α overcomes a characteristic value α*, two quantum critical points appear which are connected by a dome-shaped critical line. Due to the paradigmatic nature of the anisotropic spin model here considered, we believe that our findings may provide useful insights into the physical origin of recent experimental results found for some innovative materials which exhibit two quantum critical points and dome-shaped phase diagrams induced by non-thermal control parameters driving a non-conventional quantum criticality
A nonconventional approach to describe classical-quantum crossover phenomena near criticality
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Phase transitions and critical properties in systems of interacting multicomponent magnetic bosons
No full textField-Induced Quantum Criticality of a Spin-1/2 Planar Ferromagnet
No full textThe low temperature critical properties and crossovers of a spin 1/2 planar ferromagnet in a longitudinal magnetic field are explored in terms of an anisotropic bosonic action, suitable to describe the spin model in the low temperature regime. This is performed adopting a procedure which combines an averaging over dynamic degrees of freedom and the classical Wilson renormalization transformation. We get the phase boundary, ending in a quantum critical point, and general expressions for the correlation lenght and the susceptibility within the disordered phase
Renormalization group and variational treatments for a d-dimensional sine-Gordon model with correlated random fields
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Unconventional critical behaviour in quantum systems with interactions decaying as a power law
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