spinglasses

Spinglasses are a class of disordered magnetic materials. They are characterized by a random arrangement of magnetic moments that become frozen in a particular orientation at low temperatures. This frozen state is not a simple ferromagnet or antiferromagnet where all moments align in a regular pattern. Instead, the interactions between magnetic moments are a mixture of ferromagnetic (moments aligned parallel) and antiferromagnetic (moments aligned antiparallel), with a random distribution in strength and sign. This complex interplay of interactions leads to a highly disordered ground state.

A key feature of spinglasses is the presence of a very large number of local energy minima in their phase space. When the material is cooled below a characteristic temperature, known as the spinglass transition temperature, the magnetic moments settle into one of these many possible low-energy configurations. The exact configuration achieved can depend on the cooling history, a phenomenon known as history dependence.

The behavior of spinglasses is often described by concepts from statistical mechanics and computational complexity. They exhibit phenomena such as slow relaxation of magnetic properties and aging, where the system's response to external stimuli changes over time. The study of spinglasses has provided insights into disordered systems in various fields beyond magnetism, including neural networks, optimization problems, and the behavior of glassy materials in general. While the simplest models involve a binary system of spins, real spinglasses can involve more complex magnetic ions and disordered atomic structures.