What do you mean by Kondo effect?

The Kondo effect is an unusual scattering mechanism of conduction electrons in a metal due to magnetic impurities, which contributes a term to the electrical resistivity that increases logarithmically with temperature as the temperature T is lowered (as \log(T)).

What is a Kondo lattice?

1.3 The Kondo lattice. In heavy fermion material, containing a lattice of local moments, the Kondo effect develops coherence. In a single impurity, a Kondo singlet scatters electrons without conserving momen- tum, giving rise to a huge build-up of resistivity at low temperatures.

What is a Kondo singlet?

André Erpenbeck, Guy Cohen. The Kondo effect, a hallmark of strong correlation physics, is characterized by the formation of an extended cloud of singlet states around magnetic impurities at low temperatures.

What is a heavy fermion system?

The heavy fermion (HF) systems provide the largest and most varied class of unconventional superconductors. They are intermetallic compounds containing rare-earth ions with partially filled f-shells, displaying strong correlation effects reflected in an extremely large quasiparticle mass enhancement (m?=50–1000 me).

What is hybridization gap?

Hybridization and forming of an indirect energy (hybridization) gap due to the coherent Kondo screening of the local moments by the sea of conduction electrons. In case of Kondo insulators the Fermi level (chemical potential) is located in the hybridization gap.

Which model is best suited to explain Kondo effect?

The Anderson impurity model and accompanying Wilsonian renormalization theory were an important contribution to understanding the underlying physics of the problem. Based on the Schrieffer-Wolff transformation, it was shown that the Kondo model lies in the strong coupling regime of the Anderson impurity model.

What is a heavy electron?

Electrons are one type of fermion, and when they are found in such materials, they are sometimes referred to as heavy electrons. Heavy fermion materials have a low-temperature specific heat whose linear term is up to 1000 times larger than the value expected from the free electron model.

Is a muon a fermion?

Fundamental fermions (fermions that are not made up of anything else) are either quarks or leptons. There are 6 different types of quarks (called “flavours”) and 6 different types of leptons. These are their names: Leptons — electron, muon, tau, electron neutrino, muon neutrino, tau neutrino.

Is neutrino a fermion particle?

Neutrinos are a type of fundamental particle known as a fermion. All other fermions, such as leptons and quarks, gain their mass through their interactions with the Higgs boson.

How fast do muons travel?

about 0.994c.
Muons reach earth with an average velocity of about 0.994c. On earth’s surface, about 1 muon passes through a 1 cm2 area per minute (~10,000 muons per square meter in one minute). Muon flux is constant over time.

Can an electron lose mass?

an electron, like any other “material” particle, does have a rest mass. This is a lower limit value, so under arbitrary circumstances there cannot be an electron with less mass. The key fact is that energy has mass, too. And the mass of an electron increases if the speed of the electron increases.

What do you need to know about the Kondo effect?

Kondo effect: How gold with a small amount of what were probably iron impurities behaves at low temperatures In physics, the Kondo effect describes the scattering of conduction electrons in a metal due to magnetic impurities, resulting in a characteristic change in electrical resistivity with temperature.

How is the Fermi velocity related to the Kondo effect?

Schematic of the weakly coupled high temperature situation in which the magnetic moments of conduction electrons in the metal host pass by the impurity magnetic moment at speeds of v F, the Fermi velocity, experiencing only a mild antiferromagnetic correlation in the vicinity of the impurity.

How is the Kondo effect an example of asymptotic freedom?

In contrast, as the temperature tends to zero the impurity magnetic moment and one conduction electron moment bind very strongly to form an overall non-magnetic state. The Kondo effect can be considered as an example of asymptotic freedom, i.e. a situation where the coupling becomes non-perturbatively strong at low temperatures and low energies.

What is the coupling in the Kondo problem?

In the Kondo problem, the coupling refers to the interaction between the localized magnetic impurities and the itinerant electrons.