Related papers: Quantum Lifshitz Point
In this work quantum electrodynamics at T > 0 is considered. For this purpose we use thermo field dynamics and the causal approach to quantum field theory according to Epstein and Glaser, the latter being a rigorous method to avoid the…
We have numerically studied the thermodynamic properties of the spin 1/2 XXZ chain in the presence of a transverse (non commuting) magnetic field. The thermal, field dependence of specific heat and correlation functions for chains up to 20…
We analyze the phase diagram of a quantum mean spherical model in terms of the temperature $T$, a quantum parameter $g$, and the ratio $p=-J_{2}/J_{1}$, where $J_{1}>0$ refers to ferromagnetic interactions between first-neighbor sites along…
In this paper we present an extensive study of the thermodynamic properties of the two-dimensional quantum Heisenberg antiferromagnet on the square lattice; the problem is tackled by the pure-quantum self-consistent harmonic approximation,…
Using high temperature expansions for the equal time correlator $S(q)$ and static susceptibility $\chi(q)$ for the t-J model, we present evidence for quantum critical (QC), $z\!=\!1$, behavior at intermediate temperatures in a broad range…
The Hubbard model in the Heisenberg limit is studied by Kondo-lattice theory. The Kondo temperature T_K or k_BT_K, which is an energy scale of low-energy local quantum spin fluctuations, is enhanced by the resonating valence bond (RVB)…
Strongly disordered and strongly interacting quantum critical points are difficult to access with conventional field theoretic methods. They are, however, both experimentally important and theoretically interesting. In particular, they are…
Using conformal field theory methods Eggert and Affleck have shown that the semi-infinite S=1/2 Heisenberg antiferromagnetic chain exhibits a remarkable alternation in its local response to a uniform field at low temperatures. Such…
Antiferromagnetic quantum spin systems can exhibit a transition between collinear and spiral ground states, driven by frustration. Classically this is a smooth crossover and the crossover point is termed a Lifshitz point. Quantum…
The low Curie temperature (T_C approx 28K) and small ordered moment (M_0 approx 0.17 mu_B f.u.^-1) of ZrZn2 make it one of the few examples of a weak itinerant ferromagnet. We report results of susceptibility, magnetization, resistivity and…
We report the results of low-temperature measurements of the specific heat Cp(T), ac susceptibility chi(T) and 23Na nuclear magnetic resonance NMR of Na2V3O7. At liquid He temperatures Cp(T)/T exhibits broad field-dependent maxima, which…
The thermalization of an isolated quantum system is described by quantum mechanics and thermodynamics, while these two subjects are still not fully consistent with each other. This leaves a less-explored region where both quantum and…
A crossover between logarithmic and exponential temperature dependence of the conductance (weak and strong localization) has been observed in ultrathin films of metals deposited onto substrates held at liquid helium temperatures. The…
The electrical resistance, Hall resistance and thermoelectric power of the Ising-like antiferromagnet UIrSi3 were measured as functions of temperature and magnetic field. We have observed that the unequivocally different characters of…
Thermodynamic properties of the quantum Heisenberg spin chains with S = 1/2, 1, and 3/2 are investigated using the transfer-matrix renormalization-group method. The temperature dependence of the magnetization, susceptibility, specific heat,…
We disclose the effects of Lifshitz dynamical exponent $z$ on the properties of holographic paramagnetic-ferromagnetic phase transition in the background of Lifshitz spacetime. To preserve the conformal invariance in higher dimensions, we…
We report thermoelectric and resitivity measurements of antiferromagnetic heavy fermion compound YRh2Si2 at low temperatures down and under high magnetic field. At low temperature, the thermoelectric power and the resistivity present…
Recent experimental results: (i) the measurement of the $T \ln T$ specific heat in cuprates and the earlier such results in some heavy fermion compounds, (ii) the measurement of the single-particle scattering rates, (iii) the density…
Monte Carlo simulations are performed for the S = 1/2 XY and ferro- and antiferromagnetic Heisenberg model in two dimensions using the loop algorithm. Thermodynamic properties of all these models are investigated in wide temperature range.…
We clarify that metamagnetic transitions in three dimensions show unusual properties as quantum phase transitions if they are accompanied by changes in Fermi-surface topology. An unconventional universality deeply affected by the…