ABSTRACT
Half-metallic ferromagnets are universally believed to be of great importance for a multitude of spintronic applications, including non-volatile logic and memory, spin transistors and many other recently proposed devices. While many materials have been predicted to be half-metallic, experimental confirmation of this exciting effect is still very controversial, particularly for optimally doped La(0.7)Sr(0.3)MnO(3) (LSMO). In this paper we will review some of the techniques used for spin polarization measurements and, in particular, the results obtained for LSMO. It was argued in Nadgorny et al (2001 Phys. Rev. B 63 184433) that LSMO is a transport half-metal, rather than a conventional half-metal with no minority electrons at the Fermi level at T = 0 K. We will discuss some of the more recent measurements in LSMO and see how well this conclusion stacks up against these new results.
ABSTRACT
A superconducting point contact is used to determine the spin polarization at the Fermi energy of several metals. Because the process of supercurrent conversion at a superconductor-metal interface (Andreev reflection) is limited by the minority spin population near the Fermi surface, the differential conductance of the point contact can reveal the spin polarization of the metal. This technique has been applied to a variety of metals where the spin polarization ranges from 35 to 90 percent: Ni0.8Fe0.2, Ni, Co, Fe, NiMnSb, La0.7Sr0.3MnO3, and CrO2.
