https://doi.org/10.1140/epjb/e2011-20621-0
Regular Article
Quantum tricriticality in transverse Ising-like systems
1
Dipartimento di Fisica “E. R. Caianiello”, Università di
Salerno, 84084
Fisciano ( Salerno), Italy
2
CNISM, Unità di Salerno, 84084
Fisciano ( Salerno), Italy
3
Dipartimento di Scienze Fisiche, Università di Napoli Federico
II, 80125
Napoli,
Italy
a e-mail: mtm@physics.unisa.it
Received:
27
July
2011
Received in final form:
4
October
2011
Published online:
23
November
2011
The quantum tricriticality of d-dimensional transverse Ising-like systems is studied by means of a perturbative renormalization group approach focusing on static susceptibility. This allows us to obtain the phase diagram for 3 ≤ d < 4, with a clear location of the critical lines ending in the conventional quantum critical points and in the quantum tricritical one, and of the tricritical line for temperature T ≥ 0. We determine also the critical and the tricritical shift exponents close to the corresponding ground state instabilities. Remarkably, we find a tricritical shift exponent identical to that found in the conventional quantum criticality and, by approaching the quantum tricritical point increasing the non-thermal control parameter r, a crossover of the quantum critical shift exponents from the conventional value φ = 1/(d − 1) to the new one φ = 1/2(d − 1). Besides, the projection in the (r,T)-plane of the phase boundary ending in the quantum tricritical point and crossovers in the quantum tricritical region appear quite similar to those found close to an usual quantum critical point. Another feature of experimental interest is that the amplitude of the Wilsonian classical critical region around this peculiar critical line is sensibly smaller than that expected in the quantum critical scenario. This suggests that the quantum tricriticality is essentially governed by mean-field critical exponents, renormalized by the shift exponent φ = 1/2(d − 1) in the quantum tricritical region.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2011
