相关论文: Critical exponents of the quantum phase transition…

We present high precision estimates of the exponents of a quantum phase transition in a planar antiferromagnet. This has been made possible by the recent development of cluster algorithms for quantum spin systems, the loop algorithms. Our…

I use the two-step density-matrix renormalization group method to extract the critical exponents $\beta$ and $\nu$ in the transition from a N\'eel $Q=(\pi,\pi)$ phase to a magnetically disordered phase with a spin gap. I find that the…

We simulate the spin-1/2 Heisenberg model with a spatially staggered anisotropy using first principles Monte Carlo method. In particular, the critical exponents $\beta/\nu$ and $\omega$ associated with the quantum phase transition induced…

We study the critical properties in cubic systems of antiferromagnetically coupled spin dimers near magnetic-field induced quantum phase transitions. The quantum critical points in the zero-temperature phase diagrams are determined from…

We study the N\'eel-paramagnetic quantum phase transition in two-dimensional dimerized $S=1/2$ Heisenberg antiferromagnets using finite-size scaling of quantum Monte Carlo data. We resolve the long standing issue of the role of cubic…

In Phys. Rev. Lett. 84, 4204 (2000) (cond-mat/9905379), Kato et al. presented quantum Monte Carlo results indicating that the critical concentration of random non-magnetic sites in the two-dimensional antiferromagnetic Heisenberg model…

The quantum ferromagnetic transition of itinerant electrons is considered. We give a pedagogical review of recent results which show that zero-temperature soft modes that are commonly neglected, invalidate the standard…

Quantum-critical behavior of the itinerant electron antiferromagnet (V0.9Ti0.1)2O3 has been studied by single-crystal neutron scattering. By directly observing antiferromagnetic spin fluctuations in the paramagnetic phase, we have shown…

We present large-scale Monte-Carlo simulations of a two-dimensional (2d) bilayer quantum Heisenberg antiferromagnet with random dimer dilution. In contrast to the exotic scaling scenarios found in many other random quantum systems, the…

We study one-dimensional itinerant ferromagnets with Heisenberg symmetry near a ferromagnetic quantum critical point. It is shown that the Berry phase term arises in the effective action of itinerant ferromagnets when the full SU(2)…

Criticality of chiral phase transition at finite temperature is investigated in a soft-wall AdS/QCD model with $SU_L(N_f)\times SU_R(N_f)$ symmetry, especially for $N_f=2,3$ and $N_f=2+1$. It is shown that in quark mass plane($m_{u/d}-m_s$)…

Critical exponents in the CP^{N-1} model, which describes localized-moment ferro- and antiferromagnets (N=2 in the Heisenberg model), are calculated from two-particle Green's functions to first order in 1/N. For d=2+\epsilon the results…

We study the phase diagram of the four dimensional O(4) model with first (beta1) and second (beta2) neighbor couplings, specially in the beta2 < 0 region, where we find a line of transitions which seems to be second order. We also compute…

We improve the theoretical estimates of the critical exponents for the three-dimensional Heisenberg universality class. We find gamma=1.3960(9), nu=0.7112(5), eta=0.0375(5), alpha=-0.1336(15), beta=0.3689(3), and delta=4.783(3). We consider…

We report a novel critical exponent delta=3/2 of magnetization curves M=H^{1/delta} near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3 (A = Ca, La0.5Na0.5, and La), which the mean field theory of the Ginzburg-Landau-Wilson type…

We present numerical results for an $S=1/2$ Heisenberg antiferromagnet on a inhomogeneous square lattice with tunable interaction between spins belonging to different plaquettes. Employing Quantum Monte Carlo, we significantly improve on…

The static critical phenomenology near the Curie temperature of the re-entrant metallic alloys Au_0.81Fe_0.19, Ni_0.78Mn_0.22, Ni_0.79Mn_0.21 and amorphous a-Fe_0.98Zr_0.08 is studied using a variety of experimental techniques and methods…

Ground-state magnetic properties of the diluted Heisenberg antiferromagnet on a square lattice are investigated by means of the quantum Monte Carlo method with the continuous-time loop algorithm. It is found that the critical concentration…

We present the results of a Monte Carlo simulation of the antiferromagnetic RP(2) model in three dimensions. With finite-size scaling techniques we accurately measure the critical exponents and compare them with those of O(N) models. We are…

We obtain the complete phase diagram of the antiferromagnetic $J_{1}$-$J_{2}$ model, $0\leq \alpha = J_2/J1 \leq 1$, within the framework of the $O(N)$ nonlinear sigma model. We find two magnetically ordered phases, one with N\' eel order,…