Spin (physics) - Applications

Applications

Spin has important theoretical implications and practical applications. Well-established direct applications of spin include:

• Nuclear magnetic resonance spectroscopy in chemistry;
• Electron spin resonance spectroscopy in chemistry and physics;
• Magnetic resonance imaging (MRI) in medicine, which relies on proton spin density;
• Giant magnetoresistive (GMR) drive head technology in modern hard disks.

Electron spin plays an important role in magnetism, with applications for instance in computer memories. The manipulation of nuclear spin by radiofrequency waves (nuclear magnetic resonance) is important in chemical spectroscopy and medical imaging.

Spin-orbit coupling leads to the fine structure of atomic spectra, which is used in atomic clocks and in the modern definition of the second. Precise measurements of the g-factor of the electron have played an important role in the development and verification of quantum electrodynamics. Photon spin is associated with the polarization of light.

A possible future direct application of spin is as a binary information carrier in spin transistors. Original concept proposed in 1990 is known as Datta-Das spin transistor. Electronics based on spin transistors is called spintronics, which includes the manipulation of spins in semiconductor devices.

There are many indirect applications and manifestations of spin and the associated Pauli exclusion principle, starting with the periodic table of chemistry.