Magnetization Depth Profile in a Magnetic Insulating Film Under a Thermal Gradient*

By eliminating mobile electrons, insulator spintronics offer opportunities to reduce power loss and signal decay of metallic interconnects in complicated integrated circuits. As a consequence, there are no energy losses due to the heating by the conducting electrons or eddy currents. This strategy requires methods to generate, transport, and detect the spin and transfer them into a charge-based signal for further processing. A temperature gradient has been shown to generate a pure spin current inside a magnetic insulator that could be detected in an adjacent metallic film with a high spin-orbital angle (spin Seebeck effect, SSE). Little experimental evidence is known about the depth dependence of spin structure. Using a similar sample design, we have measured the polarized neutron reflectivity (PNR) from a YIG film with and without a temperature gradient. We will present the magnetization as a function of depth in the magnetic insulator extracted from the PNR along with structural, magnetic, and electric transport characterization. We have observed a larger than expected magnetization in the GGG substrate which may contribute to the size of the SSE in similar samples.