Theory of spin-polarized STM for spin liquids

We investigate theoretically the spin-polarized scanning tunneling microscopy as a probe for quantum spin liquids. We calculate the tunneling electric currents for various magnetic states and spin liquids as a function of external magnetic field and magnetization of the spin-polarized tip. From the calculation, we will identify characteristic I-V curves for U(1) and Z2 quantum spin liquids, which can be differentiated from more conventional magnetic states. On top of this, we will also consider a magnetic analogue of the Friedel oscillation induced by a local spin impurity, which may help to identify spinon Fermi surfaces in experimental setups.