Disappearance of the Spin Gap in a Zn doped 2-Leg Ladder Compound Sr(Cu1-xZnx)2O3

TL;DR

This study used inelastic neutron scattering to examine how nonmagnetic Zn impurities affect the spin gap in a 2-leg ladder compound, revealing the gap's robustness and the emergence of in-gap states.

Contribution

It provides new insights into impurity effects on quantum spin systems, showing the spin gap remains unchanged while in-gap states develop with Zn doping.

Findings

Spin gap remains at 33 meV despite Zn doping

In-gap density of states increases with Zn concentration

Magnetic specific heat shows T-linear behavior

Abstract

An inelastic neutron scattering study was performed on a Zn-substituted spin-1/2 Heisenberg 2-leg ladder compound Sr(Cu1-xZnx)2O3 (x < 0.04) to investigate nonmagnetic impurity effects on the quantum spin system with a large spin gap of about 400 K. The magnitude of the spin gap was found to be independent of Zn concentration, 33 meV, while the integrated magnetic scattering which corresponds to the singlet-triplet excitation decreased monotonically with increasing x. On account of the total-sum rule, this result supports the existence of a finite in-gap density of states at E = 0 which was suggested from the T-linear magnetic specific heat.