Superfluid density and volume fraction of static magnetism in stripe-stabilized La 1.85− yEu ySr 0.15CuO 4

Abstract

Muon spin relaxation measurements have been performed in the optimally doped La 1.85− y Eu y Sr 0.15CuO 4, where the static spin stripes are stabilized by the rare-earth doping. Zero-field measurements indicate that the volume fraction V Cu of static magnetism increases with increasing Eu concentration, while the ordered moment size remains constant. Transverse-field measurements show that n s /m ∗ (superconducting carrier density/effective mass) at T→0 is proportional to the non-magnetic volume fraction (1− V Cu). These results indicate that superconductivity and static stripe magnetism occur in different spatial regions, exclusively, suggestive of microscopic phase separation.