All articles A–Z

Spillway bridge

A spillway bridge is a bridge deck carried on or across a dam spillway crest or gate structure, providing roadway access, gate-hoist support, and operator access over the flow surface.

Spillway hydraulics and safety

Spillway hydraulics and safety is the engineering analysis of whether a dam's spillway and outlet works can pass extreme floods without overtopping the dam or failing.

Spin (aerodynamics)

A spin, also called a tailspin, is an aggravated stall in which an airplane descends in a corkscrew path while rotating, with at least one wing stalled.

Spin (physics)

Spin (physics), also called quantum mechanical spin, is the intrinsic angular momentum of particles, a fixed property like mass and charge that does not come from physical rotation.

Spin (propaganda): the deliberate, biased interpretation of events in political communication and public relations, performed by spin doctors; the term broadened after about 1992 and was established in UK discourse by New Labour in 1997.

SPIN (Self-Play Fine-Tuning)

SPIN (Self-Play fIne-tuNing) is a post-training method for large language models, introduced at UCLA in 2024, that improves a model using its own generated responses.

Spin angular momentum of light

The spin angular momentum of light, distinct from orbital angular momentum, is the angular momentum light carries by virtue of its polarization, with each circularly polarized photon carrying ±ħ.

Spin bowling

Spin bowling is a cricket bowling method in which the bowler rotates the ball so it deviates after pitching, typically at slower speeds than fast bowlers.

Spin chain

A spin chain is a one-dimensional array of quantum spins coupled by a Hamiltonian, serving as the simplest setting for studying quantum magnetism, entanglement, and integrable systems.

Spin City

Spin City (1996–2002) is an ABC sitcom created by Gary David Goldberg and Bill Lawrence about New York Deputy Mayor Mike Flaherty (Michael J. Fox) managing Mayor Randall Winston; Charlie Sheen led the final two seasons after Fox left.

Sep 29, 2026

Spin coating

Spin coating is a thin-film deposition technique in which a liquid on a rapidly spinning substrate spreads into a thin, uniform layer, used for photoresists and solar cells.

Spin connection

The spin connection is a connection on the bundle of orthonormal frames of a metric-equipped manifold, written as a one-form with one spacetime index and two Lorentz indices.

Spin crossover

Spin crossover is a phenomenon in molecular magnetism where temperature, pressure, or light switches a transition-metal complex between high-spin and low-spin states, first reported around 1930.

Spin current

A spin current is a flow of spin angular momentum in condensed matter, the spin counterpart of electric current, where spins are transported without or with charge flow.

Spin defects in hexagonal boron nitride

Spin defects in hexagonal boron nitride are atomic defects whose electron spins are optically controllable, making the 2D material a platform for quantum sensing and qubits.

Spin density wave

A spin density wave (SDW) is a periodic modulation of electron spin density in a metal, carried by mobile conduction electrons; chromium shows one below 311 K.

Spin Doctors

Spin Doctors, American alternative rock band formed in New York City in 1988, grew from the Trucking Company with John Popper. Known for the 1991 multi-platinum Pocket Full of Kryptonite and hits "Two Princes" and "Little Miss Can't Be Wrong"; still active with Face Full of Cake (2025).

Spin dynamics

Spin dynamics is the accelerator-physics study of how particle spin precesses and depolarizes in ring fields, described by the Thomas-BMT equation, with Sokolov-Ternov self-polarization and Siberian Snakes preserving beam polarization.

Spin echo

The spin echo, also called the Hahn echo, is an NMR signal revived by radiofrequency pulses; Erwin Hahn discovered it in 1950, and it underlies MRI.

Spin exciton

A spin exciton, also called a magnetic exciton, is a quasiparticle bound to an ordered spin background in a magnet. It is best studied in NiPS₃.

Spin foam model

A spin foam model is a path-integral state sum over 2-complexes with spin-labeled faces and intertwiner-labeled edges, extending loop quantum gravity's spin networks to quantum spacetime.

Spin foam models

Spin foam models are state-sum formulations of non-perturbative, background-independent quantum gravity, closely related to loop quantum gravity, computing transition amplitudes between quantum states as sums over spin foams.

Spin glass

A spin glass is a magnetic material whose atomic moments freeze into random directions at low temperature, combining quenched disorder and frustration with slow, history-dependent aging dynamics.

Spin Hall effect

The spin Hall effect is a phenomenon in which electrical current in a non-magnetic conductor generates a transverse spin current without magnetic fields, first observed in 2004.

Spin Hall magnetoresistance

Spin Hall magnetoresistance (SMR) is a magnetization-dependent resistance change in heavy metals like platinum or tungsten next to a magnetic layer, first observed in platinum/YIG bilayers in 2013.

Spin Hall magnetoresistance in antiferromagnets

Spin Hall magnetoresistance in antiferromagnets (SMR) is a resistance change in a heavy metal such as platinum contacting an antiferromagnet, reflecting its magnetic order's orientation.

Spin Hall nano-oscillator

A spin Hall nano-oscillator (SHNO) is a nanoscale spintronic device in which spin Hall effect spin currents drive magnetic precession, generating tunable microwave signals for neuromorphic computing.

Spin ice

Spin ice is a magnetic state of matter in certain crystals whose moments obey two-in, two-out ice rules on tetrahedra, mirroring proton disorder in water ice and carrying residual entropy.