Quantum spin liquids with tunable Fermi surfaces in spin-chain arrays

We introduce a lattice spin-1/2 model that realizes a U(1) quantum spin liquid with a tunable Fermi surface as its ground state. Using bosonization techniques, we introduce a coupled spin-chain model that maps exactly onto a theory of two spinons coupled to an emergent photon. These spinons form a Fermi surface, whose volume can be tuned via the parameters of the microscopic wire model. Finally, we construct a lattice spin Hamiltonian with two- and four-spin terms that generate the analyzed wire model.