In situmagnetometry with polarized neutrons on thin magnetic films

We shall discuss perspectives opened up by using polarized neutron reflectometry as an in situ technique to measure the magnetization of ultrathin films not covered by a protective layer. In order to demonstrate the advantage of this method, Fe(110) films of a thickness of up to 20 {} were prepared on V(110) single crystals. In neutron measurements the absolute value of the magnetization of the films was determined precisely by a simple optical model, by fitting the spin-up and spin-down reflectivities separately. Additionally the measurements were compared with data obtained from magneto-optical Kerr magnetometry. Both techniques show that the magnetizations of the films are considerably reduced.