IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+NS-ThM

Invited Paper MI+NS-ThM1
Measurement of Spin Polarization using Andreev Reflection

Thursday, November 1, 2001, 8:20 am, Room 110

Session: Magnetic Imaging and Spectroscopy
Presenter: R.J. Soulen, Naval Research Laboratory
Authors: R.J. Soulen, Naval Research Laboratory
M.S. Osofsky, Naval Research Laboratory
G. Trotter, Naval Research Laboratory
Correspondent: Click to Email
Measurement of spin polarization using Andreev reflection A new class of electronics is emerging which relies on the ability of ferromagnetic materials to conduct spin polarized currents. The performance of devices based on this phenomenon is greatly enhanced as the spin polarization, P, of the ferromagnetic material approaches 100%. In the face of difficulties in measuring this important property, we have developed a very simple method to determine P in which a superconducting point is placed in contact with the candidate ferromagnetic material. The Andreev reflection process at the interface between the two metals is influenced by the spin polarization of the ferromagnet enabling the determination of P through measurement of the conductance of the contact. In a very short time we have been able to measure the spin polarization of several metals and conducting oxides: NixFe1-x; Ni. Co, Fe, NiMnSb, La0.7Sr0.3MnO3; CrO2, whose spin polarization ranges from 25% to over 90%. Our results compare well with other magnetic spectroscopy measurements of P where available. Our search continues for a material with 100% spin polarization.