However, some compounds have been found which show insulating behavior even for partially filled bands.

A significant number of electrons are thermally excited into empty levels, creating holes in the filled band.

We note that the Chern number of a filled band can only characterize a particular kind of topological order - integral quantum Hall state.

The beautiful floral pearl encrusted heart and lacy Hardanger bottom enclose some heart filled bands that express the theme of love.

Dipropylamine tetracyanoquinodimethane, DPA TCNQ2, is by stoichiometry a 1:2 organic salt giving rise to a filled band quasi one dimensional electronic system. Conductivity measurements indicate the presence of at least three phase transitions.

The classical band structure of solid state physics predicts the Fermi level to lie in a band gap for insulators and in the conduction band for metals, which means metallic behavior is seen for compounds with partially filled bands.

However, some compounds have been found which show insulating behavior even for partially filled bands.

A significant number of electrons are thermally excited into empty levels, creating holes in the filled band.

We note that the Chern number of a filled band can only characterize a particular kind of topological order - integral quantum Hall state.

The beautiful floral pearl encrusted heart and lacy Hardanger bottom enclose some heart filled bands that express the theme of love.

Dipropylamine tetracyanoquinodimethane, DPA TCNQ2, is by stoichiometry a 1:2 organic salt giving rise to a filled band quasi one dimensional electronic system. Conductivity measurements indicate the presence of at least three phase transitions.

The classical band structure of solid state physics predicts the Fermi level to lie in a band gap for insulators and in the conduction band for metals, which means metallic behavior is seen for compounds with partially filled bands.

Both requirements for conductivity are therefore fulfilled: strong delocalization and partly filled energy bands.

Previously, the measurement of geometric phases in solids could only be carried out indirectly, and required a filled energy band for the measurement.

This kind of topological order corresponds to integral quantum Hall state, which can be characterized by the Chern number of the filled energy band if we consider integer quantum Hall state on a lattice.