Nonmagnetic-magnetic Transitions in Rutile RuO2

TL;DR

This study uses density functional theory to explore how strain and electronic correlations influence the magnetic states of RuO₂, revealing multiple magnetic phases and transitions between magnetic and nonmagnetic states.

Contribution

It uncovers strain-dependent magnetic phase transitions and identifies multiple altermagnetic phases in RuO₂, clarifying its controversial magnetic ground state.

Findings

Multiple altermagnetic phases identified in Hubbard parameter space.

Strain induces transitions between nonmagnetic and magnetic states.

Potential applications in spintronics due to tunable magnetism.

Abstract

Rutile RuO$_2$ has attracted great interest recently, as its magnetic ground state remains controversial. Experimental studies have reported either nonmagnetic or altermagnetic (AM) ground states in different crystalline samples of RuO$_2$, highlighting the need for a reasonable explanation to resolve this contradiction. In this study, density functional theory calculations are performed to reveal the correlation-sensitive and strain-dependent magnetism of bulk RuO$_2$. On one hand, multiple AM phases with different magnitudes of the spin magnetic moment are identified in the Hubbard parameter space for RuO$_2$. On the other hand, when appropriate strains which significantly change the crystal cell volume are applied, the ground state of RuO$_2$ can undergo transitions between the nonmagnetic state with no spin splitting and the magnetic states with spin splitting in the band structure. These findings not only demonstrate intriguing physics in 4d-electron-correlated RuO$_2$, but also retain its potential for spintronic applications.