Magnetic impurity in a U(1) spin liquid with a spinon Fermi surface

We address the problem of a magnetic impurity in a two-dimensional U(1) spin liquid where the spinons have gapless excitations near the Fermi surface and are coupled to an emergent gapless gauge field. Using a large N expansion, we analyze the strong coupling behavior and obtain the Kondo temperature which was found to be the same as for a Fermi liquid. In this approximation, we also study the specific heat and the magnetic susceptibility of the impurity. These quantities present no deviations from the Fermi liquid ones, consistent with the notion that the magnetic impurity is only sensitive to the local density of fermionic states.