Emergence of low temperature glassy dynamics in Ru substituted non magnetic insulator CaHfO3

TL;DR

This study demonstrates how Ru substitution in non-magnetic CaHfO3 induces low-temperature glassy magnetic dynamics, revealing a transition from diamagnetic to glassy states due to competing interactions among Ru ions.

Contribution

It uncovers the emergence of glassy magnetic behavior in CaHfO3 caused by Ru doping, with detailed analysis of the magnetic states and underlying interactions.

Findings

Ru substitution does not alter crystal structure up to 50%

A crossover from diamagnetic to paramagnetic occurs at 20% Ru

Glass-like magnetic behavior appears for x > 0.25 at low temperatures

Abstract

Non magnetic insulators/semiconductors with induced magnetism introduced via transition metal substitution are one of the promising materials in the field of spintronic, magnetoelectronics and magneto optical devices. In this context, here, we focus on magnetism induced in a non magnetic insulator CaHfO3, by the substitution of 4d element Ru, at Hf site. Structural investigations indicate that substitution of Ru4+ (up to 50%) does not affect the original crystal structure of the parent compound. Magnetic studies divulge a crossover from a diamagnetic to paramagnetic state with 20% Ru substitution. Further replacement of Hf results in a glassy magnetic state in CaHf1-xRuxO3 (0.3 < x < 0.5). The nature of the low temperature glassiness (below 20 K) in these compositions is confirmed through Vogel Fulcher and Power law, along with, magnetic memory effect and relaxation dynamics. The observed glassiness is explained through the phenomenological hierarchical model. Our studies indicate that the presence of competing short range interactions among randomly arranged Ru cations in non magnetic insulator CaHfO3 are responsible for the observed low temperature magnetic state in this series with compositions > 0.25.