Interplay of quantum and thermal fluctuations in a frustrated magnet

Abstract

We demonstrate the presence of an extended critical phase in the transverse field Ising magnet on the triangular lattice, in a regime where both thermal and quantum fluctuations are important. We map out a complete phase diagram by means of quantum Monte Carlo simulations, and find that the critical phase is the result of thermal fluctuations destabilising an order established by the quantum fluctuations. It is separated by two Kosterlitz-Thouless transitions from the paramagnet on one hand and the quantum-fluctuation driven three-sublattice ordered phase on the other. Our work provides further evidence that the zero temperature quantum phase transition is in the 3d XY universality class.

Nematic Quantum Critical Fluctuations inBaFe2−xNixAs2Liu1, Gu2, Zhang3 et al. 2016Phys. Rev. Lett.496751View full textAdd to dashboardCite

“…However, since nematic quantum critical fluctuations should manifest themselves in the charge channel due to their coupling to fermions, the nematic signal may be observed along the (100) direction in the resistivity measurement since the fermions may be scattered more isotropically around the QCP [19]. Moreover, it is also possible that a higher symmetry may present around the QCP, as shown both theoretically and experimentally [21][22][23][24][25]. In any case, the signal observed along the (100) direction may be treated as a sign of nematic quantum fluctuations.…”

“…Consequently, the pressure-dependent resistivity may also exhibit some degree of isotropy. In addition, we cannot rule out the possibility that a higher symmetry may be present around the QCP as suggested both theoretically [21,22,24] and experimentally in the one-dimensional Ising chain system in the transverse field [25].…”

Critical Properties of the Kitaev-Heisenberg Model

“…We argue that the classical KH model effectively behaves like a six-state clock model [18][19][20][21] and that it undergoes two continuous phase transitions as a function of temperature separating three phases: a low-T ordered phase, an intermediate critical phase, and a high-T disordered phase. The critical phase has an emergent, continuous U (1) symmetry which is fully analogous to the low-T phase of the XY model, a well-known KT phase of critical points with floating exponents and algebraic correlations.…”

Disorder line and incommensurate floating phases in the quantum Ising model on an anisotropic triangular lattice

“…This approach makes the simulation algorithm non-local, memory efficient and allows one to work explicitly in the ǫ → 0 limit. 9,26 Measured quantities include the real space spin correlations C(r),…”

“…Transverse field Ising models with dipolar interactions have also been considered 14 in the context of solid state systems such as the glassy low temperature properties of LiHo x Y 1−x F 4 . 15 In this paper we calculate the thermodynamics and phase transitions in several specific instances of the transverse field Ising model in two spatial dimensions, using a combination of high temperature and high field series expansions 16,17 and continuous time Quantum Monte Carlo (CTQMC) approaches 5,9,18 . Our motivations are twofold.…”