Measurement of conduction-electron polarization via the pairing resonance

Y. M. Xiong, Louisiana State University
P. W. Adams, Louisiana State University
G. Catelani, Rutgers University–New Brunswick


We show that the pairing resonance in the Pauli-limited normal state of ultrathin superconducting Al films provides a spin-resolved probe of conduction-electron polarization in thin magnetic films. A superconductor- insulator-ferromagnet tunneling junction is used to measure the density of states in supercritical parallel magnetic fields that are well beyond the Clogston-Chandresekhar limit, thus greatly extending the field range of the tunneling density of states technique. The applicability and limitations of using the pairing resonance as a spin probe are discussed. © 2009 The American Physical Society.