Spin susceptibility in superconducting LiFeAs studied by polarized neutron diffraction

The local spin susceptibility in superconducting LiFeAs was studied by polarized neutron diffraction as a function of temperature. In the superconducting phase the spin susceptibility is clearly suppressed and it can be well described by the Yosida function suggesting a singlet pairing to occur at low temperature. The spin susceptibility in the normal state and its suppression in the superconducting phase are fully comparable to observations in Co-doped BaFe${}_{2}$As${}_{2}$.