Spin Susceptibility in Underdoped Cuprates: Insights from a Stripe-Ordered Crystal

TL;DR

This study investigates the spin susceptibility in underdoped cuprates, revealing that localized Cu moments dominate magnetic response and challenging previous assumptions about free carrier contributions, with implications for understanding high-temperature superconductivity.

Contribution

The paper provides a detailed quantitative analysis showing localized Cu moments dominate spin susceptibility in underdoped cuprates, revising previous interpretations and extending findings across different doping levels.

Findings

Localized Cu moments dominate magnetic response.

Field-induced spin-flop transition confirms local moments.

Free carrier contribution is minimal, contrary to prior assumptions.

Abstract

We report a detailed study of the temperature and magnetic-field dependence of the spin susceptibility for a single crystal of La(1.875)Ba(0.125)CuO(4). From a quantitative analysis, we find that the temperature-dependent anisotropy of the susceptibility, observed in both the paramagnetic and stripe-ordered phases, directly indicates that localized Cu moments dominate the magnetic response. A field-induced spin-flop transition provides further corroboration for the role of local moments. Contrary to previous analyses of data from polycrystalline samples, we find that a commonly-assumed isotropic and temperature-independent contribution from free carriers, if present, must be quite small. Our conclusion is strengthened by extending the quantitative analysis to include crystals of La(2-x)Ba(x)CuO(4) with x=0.095 and 0.155. On the basis of our results, we present a revised interpretation of the temperature and doping dependence of the spin susceptibility in La(2-x)(Sr,Ba)(x)CuO(4).