Structural modulation driven Curie temperature enhancement in Cr-doped SrRuO3

TL;DR

This study investigates how Cr-doping in SrRuO3 enhances its Curie temperature through structural modulation, octahedral distortion, and changes in electronic and magnetic properties, revealing a transition from itinerant to localized ferromagnetism.

Contribution

It provides a detailed analysis of the structural, spectroscopic, and magnetic changes induced by Cr-doping, elucidating the origin of Curie temperature enhancement in SrRuO3.

Findings

Cr-doping increases the Curie temperature by ~22 K at x=0.15.

Cr-doping causes significant octahedral distortion and unit cell volume reduction.

It suppresses complex magnetism and transitions from itinerant to localized ferromagnetism.

Abstract

Strongly correlated system with competing ground states are often poised close to the quantum critical point. External perturbations such as pressure, strain, electric field, and chemical doping can stabilise its ground state with exotic physical properties. Cr-doping is the lone exception which enhances the Curie-temperature in one of such correlated system SrRuO$_3$. To find the origin of $T_C$ enhancement, we investigate temperature-dependent structure, spectroscopic, magnetic and magnetotransport properties in SrRu$_{1-x}$Cr$_x$O$_3$. Cr-doping squeezes the unit cell volume which effectively enhances the stretching octahedral distortion by nearly five times than pure SrRuO$_3$. The Curie temperature increment by $\sim$ 22 K for x = 0.15 is found to be intertwined with the structural-modulation. Temperature-dependent Neutron diffraction analysis indicate that the unit cell volume minima coincide exactly with the enhanced ferromagnetic ordering ($\sim$ 190 K). Further analysis reveals that the effect of Cr-doping not only freezes the octahedral tilt below 100 K but also suppresses the complex magnetism responsible for exchange bias and topological hall effect in SrRuO$_3$. The spectroscopic measurements find a reduction of itinerancy of d-electrons with Cr-doping. The magnetotransport measurements portray an evolution from itinerant to localised ferromagnetism.