Point contact Andreev reflection studies on the low TCurie ferromagnet NdNi5 using a superconducting Nb tip

Abstract

We report measurement of transport spin polarization (Pt) using point contact Andreev reflection (PCAR) spectroscopy on NdNi5, a ferromagnet with Curie temperature of View the MathML source, using superconducting Nb tip View the MathML source. Detail analysis of the spectra shows that the normalized value of Pt(=Pt(T)/Pt(T=0)) for contacts with different Z follows closely the temperature variation of spontaneous magnetization, though the value of Pt decreases with increasing Z. We also observe a large decrease in superconducting quasiparticle lifetime arising from critical spin fluctuations close to the Curie temperature of the ferromagnet.