Superconductors

Heat

An unwanted byproduct of the process of converting household electric power into a current that can be used by the device.

I^2*R

Mathematical form of the line loses produced by the transmission of the electrical power

By transmitting using a higher voltage

How can the losses be reduced

Heike Kamerlingh Onnes

The Dutch physicist in 1911, in the Leiden University, who was looking at the temperature dependence of the resistance of the element mercury

linearly decreasing

Normally mercury’s resistance was __________________ with the decreasing temperature

Liquid helium

What was used to cool the Mercury sample

4.2 K or -269.2 °C

The critical temperature of a mercury

Critical temperature

The temperature below which a material loses its electrical resistance (absolute zero resistance), allows for the efficient power transmission.

Superconductivity

A property shown by some materials of conducting electricity without any electrical resistance

Alloy

A substance made by combining two or more elements, where the primary element is a metal.

Niobium-nitride

An alloy that was found to be superconductive at 16K (-257°C), in 1941

Vanadium-silicon

An inter-metallic compound that was found to be superconductive at 17.5K (-255.7°C), in 1953

Liquid nitrogen

A liquid that is commonly used for the purpose of refrigeration

Dr. Ching Wu Chu

The physicist who headed the team of researchers of Houston University, that fabricated a brittle, ceramic compound with the critical temperature of 92K (-181°C)

Yttrium barium copper oxide (YBCO)

The compound which the ceramic material with a critical temperature of 92K (-181°C) was composed of. That compound acted as an insulator at a room temperature.

Persistent supercurrent

Phenomenon where an electric current flows indefinitely without decay in a closed loop of superconducting material, even without any external voltage source.

Meissner effect

A phenomenon achieved because of zero resistance, where in the superconductor, at reaching a certain temperature, where the magnetic field within it has also reached zero. That allows us to utilize that for magnetic levitation

Yamanashi Maglev Test Line

A Japanese test track for superconducting maglev trains, which is used to develop and demonstrate high-speed magnetic levitation technology. Was opened in April 3rd, 1997.

MLX01

A Japanese maglev test vehicle to attain the speed of 603km/h

Critical magnetic field

Maximum strength of the magnetic field that destroys superconductivity.

Type I superconductors

The total 30 pure metals that exhibit zero resistivity below their critical temperature and exhibits a Meisner effect

Their superconductivity exists only below their critical temperature and magnetic field strength

The critical magnetic field for these superconductors is quite low.

Type II superconductors

The superconductors who have a much higher critical magnetic field and they can carry much higher current densities while remaining in the superconducting state.

High-temperature superconductors

Superconducting materials that belong to the subcategory of the Type II superconductors

John Bardeen, Leon Cooper, Robert Schrieffer

Individuals who proposed the BCS theory.

Cooper pair

When two electrons move together as a team inside a superconductor, even though electrons normally repel each other. They pair up because of special vibrations in the material that makes it easier for them to glide smoothly without bumping into things - which is what stops electrical resistance.

Phonon interaction

When an electron bumps the atoms in a material, making them vibrate slightly - and those vibrations help another electron come closer instead of getting pushed away

It’s like one electron softens the path for the next one by shaking the floor a bit.

Fermion

A type of particle (like an electron) that cannot share the exact same space and state with its own identical. This particle follows special quantum rules based on its spins and not its size.

Pauli Exclusion Principle

A rule in quantum physics that says no two identical fermions can be in the same exact state at the same time

This rule is the reason why electrons in an atom fill different energy levels and spins; Each one needs its own spot with a unique set of quantum numbers

n

The principle quantum number that describes the energy of the electron

l

The orbital angular momentum quantum number that indicates the most probable distance from the nucleus

ml

The magnetic quantum number that describes the energy levels in the subshell.

ms

Electron spin quantum number that describes the orientation spin of the electron which is either up or down.

Fermi level

Highest energy level that electrons fill at absolute zero temperature in solid

Acts like a boundary level between filled and empty electron states in the material

0.001eV

The approximate size of the energy gap that forms below the Fermi level in a superconductor, allowing the Cooper pairs to exist, prevents the electron collisions, and is a key feature of the superconducting state.

Boson

A type of particle that does not follows the Pauli Exclusion Principle

BCS theory

A theory that explains superconductivity by stating that electrons form Cooper pairs through interactions with the crystal lattice and these pairs behave like bosons that can occupy the same energy state, allowing resistance free current flow.

Superconducting magnets

Magnets that are 10 times stronger than the strongest electromagnet.

Magnetometer

A device that measures magnetic field or magnetic dipole moment.

Superconducting Quantum Interference Device (SQUID)

A very sensitive magnetometer used to measure extremely subtle magnetic fields.

Consists of a superconducting current loop containing two Josephson junctions.

Josephson Junction

Formed when two superconductors are separated by a thin insulating layer, allowing a supercurrent to flow through without resistance.

Josephson Effect

The phenomenon where a supercurrent can flow across two superconductors separated by a thin insulator, as predicted by B.D. Josephson in 1962