相关论文: Antiferromagnetic criticality at a heavy-fermion q…

We discuss the interplay between anti-ferromagnetic order and polarization fluctuations in a magnetic quantum paraelectric. Using an action where anti-ferromagnetic order parameter couples to the polarization fluctuations and as well as…

Unconventional metallic states which do not support well defined single-particle excitations can arise near quantum phase transitions as strong quantum fluctuations of incipient order parameters prevent electrons from forming coherent…

We investigate the role of disorder for field-driven quantum phase transitions of metallic antiferromagnets. For systems with sufficiently low symmetry, the combination of a uniform external field and non-magnetic impurities leads…

A quantum critical point (QCP) is a singularity in the phase diagram arising due to quantum mechanical fluctuations. The exotic properties of some of the most enigmatic physical systems, including unconventional metals and superconductors,…

The canonical view of heavy fermion quantum criticality assumes a single quantum critical point separating the paramagnet from the antiferromagnet. However, recent experiments on Yb-based heavy fermion compounds suggest the presence of…

Due to weak spin-orbit coupling, the magnetic excitations of an itinerant ferromagnet become magnetic rotons, excitations with degenerate minima on a hypersphere at finite wavevector. Using self-consistent Hartree and renormalization group…

Phase transitions which occur at zero temperature when some non-thermal parameter like pressure, chemical composition or magnetic field is changed are called quantum phase transitions. They are caused by quantum fluctuations which are a…

In itinerant ferromagnets, the quenched disorder is predicted to dramatically affect the ferromagnetic to paramagnetic quantum phase transition driven by external control parameters at zero temperature. Here we report a study on Fe-doped…

In low-temperature metallic magnets, ferromagnetic (FM) and antiferromagnetic (AFM) orders can exist in a single system in different parts of the phase diagram as a function of some control parameter. These phases can be adjacent, or exist…

Discontinuous quantum phase transitions besides their general interest are clearly relevant to the study of heavy fermions and magnetic transition metal compounds. Recent results show that in many systems belonging to these classes of…

The theory of second order phase transitions is one of the foundations of modern statistical mechanics and condensed matter theory. A central concept is the observable `order parameter', whose non-zero average value characterizes one or…

CeRu$_2$Si$_2$ is a well-known heavy fermion paramagnet, and substituting Ge for Si induces antiferromagnetism. This antiferromagnetism is Ising-like and has a tricritical point in the magnetic field ($H$) -temperature ($T$) phase diagram.…

Quantum phase transitions in metals are often accompanied by violations of Fermi liquid behavior in the quantum critical regime. Particularly fascinating are transitions beyond the Landau-Ginzburg-Wilson concept of a local order parameter.…

The heavy-fermion system CeCu_{6-x}Au_x exhibits a quantum critical point at x_c = 0.1 separating nonmagnetic and magnetically ordered ground states. The pronounced non-Fermi-liquid behavior at x_c calls for a search for the relevant…

There are two views of antiferromagnets. The first proceeds from atomic physics, which predicts that atoms with unpaired electrons develop magnetic moments. In a solid, the coupling between moments on nearby ions then yields…

Recently it was argued that quantum phase transitions can be radically different from classical phase transitions with as a highlight the 'deconfined critical points' exhibiting fractionalization of quantum numbers due to Berry phase…

A growing body of evidence suggests that the quantum critical behavior at the onset of magnetism in heavy fermion systems can not be understood in terms of a simple quantum spin density wave. This talk will discuss the consequences of this…

We propose a phenomenological spin fluctuation theory for antiferromagnetic quantum tricritical point (QTCP), where the first-order phase transition changes into the continuous one at zero temperature. Under magnetic fields, ferromagnetic…

We address the global magnetic phase diagram of Kondo lattice systems. Through the distinct Fermi surface properties of the various phases at zero temperature, we argue that the phase diagram supports two classes of quantum critical point.…

We study by means of bulk and local probes the d-metal alloy Ni$_{1-x}$V$_x$ close to the quantum critical concentration, $x_c \approx 11.6\%$, where the ferromagnetic transition temperature vanishes. The magnetization-field curve in the…