Spin Glass Behavior in the Ru-1222 and Ru-1212 rutheno-cuprate families: a comparative study

TL;DR

This study demonstrates the presence of spin glass behavior in Ru-1222 rutheno-cuprates through susceptibility and magnetization measurements, highlighting differences from Ru-1212 and suggesting oxygen vacancies as a key factor.

Contribution

It provides the first comparative analysis showing spin glass behavior is specific to Ru-1222 and not observed in Ru-1212, linking it to oxygen vacancies.

Findings

Spin glass transition observed in Ru-1222 via ac susceptibility.

Suppression of spin glass features under low magnetic fields.

No spin glass behavior detected in YRu-1212 sample.

Abstract

Strong evidences of a spin glass phase on polycrystalline RuSr2Ln1.5Ce0.5Cu2O10-x (LnRu-1222, Ln = Y, Ho and Dy) is provided by ac susceptibility and dc magnetization measurements. The fingerprint of a spin glass transition, the frequency-dependent cusp in ac susceptibility vs. T measurements at low magnetic field, is observed for all LnRu-1222 samples. The strong supression of the cusp in the ac susceptibility measurement in the presence of magnetic fields as low as 500 Oe, and the results of thermoremanent magnetization (TRM) and isothermal remanent magnetization (IRM) measurements are also evidences of a spin glass behavior. By comparing these results with measurements on a YRu-1212 sample we conclude that the glassy behavior is characteristic of the Ru-1222 phase, not being observed for the studied YRu-1212 sample. We suggest that the spin glass transition occur only in the Ru-1222 phase possibly due to the larger number of oxygen vacancies present in these compounds.