Structure factor of low-energy spin excitations in a S=1/2 kagome antiferromagnet

The ground state of the S=1/2 Heisenberg antiferomagnet on kagome can be viewed as a collection of fermionic spinons bound into small, heavy singlet pairs. Low-energy magnetic excitations in this system correspond to breaking the pairs into individual spinons. We calculate the structure factor for inelastic neutron scattering from independent spinon pairs.Comment: 9 pages. Revised in response to referee reports. References adde

Unified theory of spin and charge in a ferromagnet

We derive a unified theory of spin and charge degrees of freedom in a ferromagnet. The spin-transfer torque and spin electromotive force are examined from the coarse-grained perspective of collective coordinates. The resulting equations of motion reflect a balance of conservative, gyroscopic (Berry-phase), and dissipative forces. We then expand the space of collective coordinates by adding the electric charge. The adiabatic spin-transfer torque and spin emf turn out to be a gyroscopic force; their nonadiabatic counterparts are a dissipative force.Comment: Minor revision in response to referee comment

Field theory of collinear and noncollinear magnetic order

These lecture notes from the 2023 Summer "School Principles and Applications of Symmetry in Magnetism" introduce the reader to the classical field theory of ferromagnets and antiferromagnets