What is complex conductivity?

The complex conductivity relates both the magnitude and the phase of the current density to the magnitude and phase of the applied electric field similar to the current and voltage in an ac circuit are related by the complex conductance.

Can conductivity be imaginary?

First, the apparent conductivity is equal to the electric conductivity when ω=0 , or when the imaginary part of the electric permittivity is zero. Second, the apparent permittivity becomes infinitely large for ω=0 when the imaginary part of the electric conductivity is different from zero.

What is the difference between optical conductivity and electrical conductivity?

The difference between the two phenomena is that Electrical conduction involves the resistivity of the material while optical conduction involves the dielectric constant of the material (and other parameters as the relaxation time…).

What does imaginary part of conductivity mean?

In this context, the conductivity having a complex value is nothing more than a phase lag between the electric field and the current density. Ultimately the imaginary part represents a sort of sluggishness of the charge carriers to respond to quick changes in the electric field, as if they have a lot of mass.

Why does the electrical conductivity of metal decreases with rise in temperature?

The electrical conductivity of a metal decreases with the rise in temperature because the positively charged kernels present in the electron sea also acquire mobility and obstruct the movement of valence electrons responsible for conductivity.

What is the meaning of optical conductivity?

Definition. Optical conductivity is the property of a material which gives the relationship between the induced current density in the material and the magnitude of the inducing electric field for arbitrary frequencies.

How is optical conductivity measured?

Measurement. The optical conductivity is most often measured in optical frequency ranges via the reflectivity of polished samples under normal incidence (in combination with a Kramers–Kronig analysis) or using variable incidence angles.

Why does conductivity decrease with increase?

As temperature increases, the mobility of the electrons, i.e. the ease with which they can travel through the material, decreases, thus decreasing the conductivity.

Why does electrical conductivity occur in metals?

Metals conduct electricity by allowing free electrons to move between the atoms. These electrons are not associated with a single atom or covalent bond. If there is less energy transfer between atoms, there is less conductivity. Pure silver and copper provide the highest thermal conductivity, with aluminum less so.

Why conductivity is both temperature and concentration dependent?

Conductivity is a measurement of the ability of an aqueous solution to transfer an electrical current. The current is carried by ions, and therefore the conductivity increases with the concentration of ions present in solution, their mobility, and temperature of the water.

Why is optical conductivity complex?

Optical conductivity is complex because any real material will have some nonzero absorption (i.e. some finite absorption length) for light at any positive frequency. This is essentially equivalent to saying that the index of refraction in a material medium is always complex for any nonzero frequency.

Is optical conductivity a scalar or vector function?

The optical conductivity is closely related to the dielectric function, the generalization of the dielectric constant to arbitrary frequencies. Only in the simplest case (coarse-graining, long-wavelength limit, cubic symmetry of the material), these properties can be considered as (complex-valued) scalar functions of the frequency only.

How do you measure the optical conductivity?

The optical conductivity is most often measured in the optical frequency ranges via the reflectivity of polished samples under normal incidence (in combination with a Kramers–Kronig analysis) or using variable incidence angles. For samples that can be prepared in thin slices, higher precision is usually obtainable using optical…

What is the dielectric constant?

The dielectric constant is related to the optical conductivity. The term “optical conductivity” means the electrical conductivity in the presence of an alternating electric field. The term “optical” here covers the entire frequency range, and is not restricted only to the visible region of the spectrum.