Why does helium turn into a superfluid?

When helium is cooled to a critical temperature of 2.17 K , a remarkable discontinuity in heat capacity occurs, the liquid density drops, and a fraction of the liquid becomes a zero viscosity “superfluid”. It is called the lambda point because the shape of the specific heat curve is like that Greek letter.

What temperature does helium become a superfluid?

2.17 K
He remains liquid at zero temperature if the pressure is below 2.5 MPa (∼25 atm). The liquid has a phase transition to a superfluid phase, also known as He-II, at the temperature of 2.17 K (at vapor pressure). Helium has another stable isotope, 3He.

Is liquid helium possible?

Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity. At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).

Is helium 4 a superfluid?

Superfluid helium-4 is the superfluid form of helium-4, an isotope of the element helium. A superfluid is a state of matter in which matter behaves like a fluid with zero viscosity. This is made obvious by the fact that superfluidity occurs in liquid helium-4 at far higher temperatures than it does in helium-3.

Is superfluid helium a superconductor?

These holes are spaced about 1 µm apart; in the experiments the holes were smaller and more sparse. Superfluid helium flows without viscosity, just as superconductors conduct electricity without resistance, and both are explained by similar quantum mechanical theories.

Why does superfluid occur?

Superfluidity occurs in two isotopes of helium (helium-3 and helium-4) when they are liquefied by cooling to cryogenic temperatures. It is also a property of various other exotic states of matter theorized to exist in astrophysics, high-energy physics, and theories of quantum gravity.

What is an example of a superfluid?

Examples of superfluids include helium-3 (or ³He) and helium-4 (or ⁴He). For temperatures below 2.17 K, helium-4 becomes a superfluid. Helium-3 becomes a superfluid only below 0.0025 K. Also, when superfluids are stirred, they form vortices that “rotate indefinitely” (see Fig.

How is helium 4 formed?

Helium-4 on Earth was made through radioactive decay (when an atom breaks down into smaller atoms) from other elements, and it is made after the planet cooled and became solid. One quarter of all the mass in the Universe is helium-4.

Which is a superfluid?

superfluidity, the frictionless flow and other exotic behaviour observed in liquid helium at temperatures near absolute zero (−273.15 °C, or −459.67 °F), and (less widely used) similar frictionless behaviour of electrons in a superconducting solid.

What does superfluid mean?

Definition of superfluid : an unusual state of matter noted only in liquid helium cooled to near absolute zero and characterized by apparently frictionless flow (as through fine holes)

What can you find out about superfluids and their use?

Superfluids can be used in gyroscopes, to help machines predict information about gravity movements that can’t be picked up with regular instruments only.

How do you make a superfluid?

To create the liquid and superfluid states, you cool down helium gas to a few degrees above absolute zero. This is achieved by compressing the gas, and then expelling it through a small nozzle. As the gas expands, it rapidly cools (you’ll have noticed this effect if you’ve ever used an aerosol deodorant).