Magnetization study of RuSr2Y1.5Ce 0.5Cu2O10 (Ru-1222)

TL;DR

This study investigates the magnetic properties of RuSr2Ln1.5Ce0.5Cu2O10 compounds, revealing complex magnetic ordering and reentrant magnetic behavior around 120-130 K, with implications for understanding Ru-based magnetic systems.

Contribution

The paper provides new insights into the magnetic ordering and reentrant behavior of Ru-1222 compounds synthesized under high pressure, highlighting the coexistence of antiferromagnetism and weak ferromagnetism.

Findings

Magnetic ordering occurs at TM = 152 K regardless of Ln.

Reappearance of remanent magnetization and coercive fields between 90-100 K and 120-130 K.

Saturation and effective moments consistent with low-spin Ru5+ state.

Abstract

We have studied the magnetic properties of the non-superconducting RuSr2Ln1.5Ce0.5Cu2O10 (Ln=Y, Dy and Ho, Ru-1222) compounds synthesized under high pressure (6 Gpa) at elevated temperature. The materials become magnetically ordered at TM =152(2) K regardless of Ln. The wide ferromagnetic-like hysteresis loops which open at 5 K, close themselves around Tirr= 90-100 K and the remanent magnetizations (Mrem) and the coercive fields (HC) become zero. Surprisingly, at Tirr<T< TM a reappearance of the Mrem and HC (with a peak at 120-130 K) is observed for all three samples studied. For the non-magnetic Ln=Y compound, the extracted saturation moment at 5 K and the effective paramagnetic moment are is 0.75 and 2.05 mB /Ru, values which are close to the expected 1 mB and 1.73 mB respectively, for the low-spin state of Ru5+. We argue that the Ru-1222 system becomes (i) anti-ferromagnetically (AFM) ordered at TM. In this range a metamagnetic transition is induced by the applied field (ii). At Tirr < TM, weak-ferromagnetism (W-FM) is induced by the canting of the Ru moments.