Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Two-dimensional (2D) magnets typically exhibit uniaxial anisotropy, limiting spin switching to two directions (180°).
• Engineering magnetic anisotropy is crucial for developing advanced spintronic devices.
• Current 2D magnets require significant energy for switching between magnetic states.

Purpose of the Study:

• To demonstrate a novel eightfold magnetic anisotropy in strontium ruthenium oxide (SrRuO3) monolayers.
• To investigate the mechanism for inducing spin reorientation in (SrRuO3)1/(SrTiO3) superlattices.
• To explore the potential for low-power, multistate device applications using this new anisotropy.

Main Methods:

• Fabrication of (SrRuO3)1/(SrTiO3) superlattices with varying SrTiO3 layer thicknesses.
• Experimental observation of spin reorientation and magnetic easy axis transformation.
• First-principle calculations to elucidate the underlying physical mechanisms.

Main Results:

• A previously unobserved eightfold anisotropy was demonstrated in SrRuO3 monolayers, transitioning from uniaxial <001> to eightfold <111> easy axes.
• This eightfold anisotropy enables 71° and 109° spin switching, analogous to ferroelectric switching.
• Increasing SrTiO3 layer thickness induces emergent correlation-driven orbital ordering, tuning spin-orbit interactions and reorienting the easy axis.

Conclusions:

• Correlation effects can be harnessed to engineer spin-orbit interactions and stabilize unprecedented magnetic properties in 2D materials.
• The discovered eightfold anisotropy in SrRuO3 monolayers opens opportunities for multistate, low-power spintronic devices.
• This work provides a new paradigm for controlling magnetism in 2D systems beyond conventional uniaxial anisotropy.