This is an introductory review of the physics of quantum spin liquid states. Quantum
magnetism is a rapidly evolving field, and recent developments reveal that the ground states …

Quantum spin liquids may be considered'quantum disordered'ground states of spin systems,
in which zero-point fluctuations are so strong that they prevent conventional magnetic long …

This review focuses on the field of quantum entanglement applied to condensed matter
physics systems with strong correlations, a domain which has rapidly grown over the last …

Pursuing fractionalized particles that do not bear properties of conventional measurable
objects, exemplified by bare particles in the vacuum such as electrons and elementary …

NATURE abounds with phase transitions. The boiling and freezing of water are everyday
examples of phase transitions, as are more exotic processes such as superconductivity and …

It is shown that several different order parameters can be used to characterize a type of P-
and T-violating state for spin systems, that we call chiral-spin states. There is a closely …

Since the discovery of high-transition-temperature (high-T c) superconductivity in layered
copper oxides, many researchers have searched for similar behaviour in other layered metal …

A large-N expansion technique based on symplectic [Sp (N)] symmetry for frustrated
magnetic systems is proposed and applied to the square-lattice quantum antiferromagnet …

The kagome-lattice quantum Heisenberg antiferromagnet is studied by a large-N expansion
based upon groups with symplectic Sp (N) symmetry. Two distinct types of ground states are …

The spin-½ antiferromagnetic Heisenberg model on a square lattice is used to describe the
dynamics of the spin degrees of freedom of undoped copper oxides. Even though the model …