Related papers: Quantum degradation of the second order phase tran…
Using the Kondo lattice model with classical spins in infinite dimension, magnetic phase transition in the perovskite-type $3d$ transition-metal oxide (La,Sr)MnO$_3$ is theoretically studied. On the Bethe lattice, the self-consistency…
We discuss the critical properties of the three-dimensional NJL model at nonzero temperature. We show that the Z(2)-symmetric model undergoes a second order phase transition with 2d Ising exponents and its critical region is suppressed by a…
Quantum size effect-induced heat capacity of metal nanoparticles at low temperatures was predicted 79 years ago to be exponential. This, however, has not been reported until date. In defiance, we demonstrate here observation of…
Theoretically, materials that break multiple symmetries allow, under certain conditions, the formation of four-fermion condensates above the superconducting critical temperature. Such states can be stabilized by phase fluctuations. Recently…
Inelastic neutron-scattering experiments on the high-temperature superconductor La$_{1.855}$Sr$_{0.145}$CuO$_{4}$ reveal a magnetic excitation gap $\Delta$ that decreases continuously upon application of a magnetic field perpendicular to…
The nematic electronic state and its associated nematic critical fluctuations have emerged as potential candidates for superconducting pairing in various unconventional superconductors. However, in most materials their coexistence with…
Heavy fermion metals provide a prototype setting to study quantum criticality. Experimentally, quantum critical points have been identified and studied in a growing list of heavy fermion compounds. Theoretically, Kondo destruction has…
The study of the competition or coexistence of different ground states in many-body systems is an exciting and actual topic of research, both experimentally and theoretically. Quantum fluctuations of a given phase can suppress or enhance…
We present an ab initio quantum theory of the finite temperature magnetism of iron and nickel. A recently developed technique which combines dynamical mean-field theory with realistic electronic structure methods, successfully describes the…
We report measurements of in-plane electrical and thermal transport properties in the limit $T \rightarrow 0$ near the unconventional quantum critical point in the heavy-fermion metal $\beta$-YbAlB$_4$. The high Kondo temperature $T_K$…
The large N limit of the Gross-Neveu model is here studied on manifolds with constant curvature, at zero and finite temperature. Using the zeta-function regularization, the phase structure is investigated for arbitrary values of the…
Quantum fluctuations and related phase transitions are of current interest from the viewpoint of fundamental physics and technological applications. Quantum phase implies a region where the quantum fluctuations of energy scale $\hbar\omega$…
In the majority of magnetic systems the surface is required to order at the same temperature as the bulk. In the present study, we report a distinct and unexpected surface magnetic phase transition, uniquely at a lower temperature than the…
We consider the temperature fluctuations of a small object. Classical fluctuations of the temperature have been considered for a long time. Using the Nyquist approach, we show that the temperature of an object fluctuates when in a thermal…
The emergence of complex and fascinating states of quantum matter in the neighborhood of zero temperature phase transitions suggests that such quantum phenomena should be studied in a variety of settings. Advanced technologies of the future…
Using recent insights obtained in heavy fermion physics on the thermodynamic singularity structure associated with quantum phase transitions, we present here an experimental strategy to establish if the zero-temperature transition in the…
We present thermal expansion alpha, magnetostriction and specific heat C measurements of \tal, which shows a quantum phase transition from a spin-gap phase to a Neel-ordered ground state as a function of magnetic field around H_{C0}->4.8T.…
The low-temperature magnetic phase diagram of the multiferroic system FeTe$_2$O$_5$Br down to 300 mK and up to 9 T is presented. Short-range magnetic correlations within the crystal layers start to develop already at $\sim$50 K, i.e., far…
We derive nonperturbative flow equations within an effective constituent quark model for two quark flavors. Heat-kernel methods are employed for a renormalization group improved effective potential. We study the evolution of the effective…
For the CuGeO3 single crystals doped with 1% of Fe the quantum critical behavior in a wide temperature range 1-40 K is reported. The critical exponents for susceptibility along different crystallographic axes are determined: a=0.34 (B //a…