Novel in-gap spin state in Zn-doped La_1.85Sr_0.15CuO_4

TL;DR

This study reveals that Zn doping in La_1.85Sr_0.15CuO_4 induces a novel in-gap spin state, with neutron scattering showing changes in magnetic excitations and the emergence of static magnetic peaks as Zn concentration increases.

Contribution

It demonstrates that Zn impurities create a new in-gap spin state in cuprate superconductors, advancing understanding of impurity effects on magnetic excitations.

Findings

Zn doping induces a novel in-gap spin state.

The in-gap state becomes larger and more static with increased Zn.

Spin gap behavior is altered by Zn impurities.

Abstract

Low-energy spin excitations of La1.85Sr0.15Cu1-yZnyO4 were studied by neutron scattering. In y=0.004, the incommensurate magnetic peaks show a well defined ``spin gap'' below Tc. The magnetic signals at omega=3 meV decrease below Tc=27 K for y=0.008, also suggesting the gap opening. At lower temperatures, however, the signal increases again, implying a novel in-gap spin state. In y=0.017, the spin gap vanishes and elastic magnetic peaks appear. These results clarify that doped Zn impurities induce the novel in-gap state, which becomes larger and more static with increasing Zn.