Renormalized phi^6 model for quantum phase transitions in systems of itinerant fermions

Abstract

We study the impact of quantum and thermal fluctuations on properties of quantum phase transitions occurring in systems of itinerant fermions with main focus on the order of these transitions. Our approach is based on a set of flow equations derived within the functional renormalization group framework, in which the order parameter is retained as the only degree of freedom, and where the effective potential is parametrized with a phi^6 form allowing for both first and second order scenarios. We find a tendency to turn the first order transitions within the bare model into second order transitions upon accounting for the order parameter fluctuations. We compute the first and second order phase boundary lines T_c as a function of a non-thermal control parameter a_2 in the vicinity of a quantum phase transition. We analyze crossovers of the shift exponent psi governing the shape of the T_c line when the system is tuned close to a quantum tricritical scenario, where a second order phase transition line terminates at a quantum tricritical point.

12 pages

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Cited by in corpus (14)

• Functional renormalization group approach to correlated fermion systems
• Proximity of Iron Pnictide Superconductors to a Quantum Tricritical Point
• Stability of Quantum Critical Points in the Presence of Competing Orders
• Turning a First Order Quantum Phase Transition Continuous by Fluctuations: General Flow Equations and Application to d-Wave Pomeranchuk Instability
• Dimensional crossovers and Casimir forces for the Bose gas in anisotropic optical lattices
• Finite temperature crossovers near quantum tricritical points in metals
• Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures
• Quantum criticality of the imperfect Bose gas in d dimensions
• CeCu_2Ge_2: Challenging our Understanding of Quantum Criticality
• Effective potential and quantum criticality for imbalanced Fermi mixtures
• Fermion-induced Dynamical Critical Point
• Fermion-induced quantum critical point in the Landau-Devonshire model
• Quantum interface unbinding transitions
• Thermal and Quantum Phase Transitions of the ${\varphi }^4$ Model