Magnettiketjut

Magnettiketjut are one-dimensional arrangements of magnetic moments that interact primarily with nearest neighbors along a single spatial direction. They occur in certain inorganic crystals with chain-like structures, in conducting polymers that host localized spins, and in artificially constructed nanoscale structures such as atomically assembled spin chains on surfaces. The physics of magnettiketjut is dominated by quantum fluctuations and reduced dimensionality, making them a central subject in the study of low-dimensional magnetism.

The behavior of magnettiketjut is commonly described by spin models, notably the Ising, Heisenberg, or XY models, with exchange coupling J between neighboring spins. Depending on the sign and magnitude of J and on magnetic anisotropy, the chain can realize ferromagnetic or antiferromagnetic ground states. In one dimension, without inter-chain coupling or strong anisotropy, true long-range order is typically suppressed at finite temperature. Quantum effects can lead to excitations such as spinons in S=1/2 chains or a Haldane gap in integer-spin chains.

Experimentally, quasi-one-dimensional magnets include copper-based oxides and molecular magnets; with advances in nanofabrication and atom manipulation, researchers construct artificial spin chains consisting of magnetic atoms on insulating or decoupled substrates. These systems provide platforms to study quantum transport of spin and coherent spin dynamics.

See also: spin chain, quantum magnetism, Heisenberg model, Bethe ansatz, Haldane conjecture.