Classical Spin Liquid Instability Driven By Off-Diagonal Exchange in Strong Spin-Orbit Magnets

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Magnetism

Background:

• Mott insulators with strong spin-orbit coupling are candidates for exotic quantum phases.
• Understanding their magnetic behavior is crucial for novel electronic applications.
• Experimental data, such as suppressed X-ray magnetic circular dichroism, requires theoretical explanation.

Purpose of the Study:

• To investigate the role of off-diagonal exchange anisotropy in Mott insulators.
• To characterize the resulting magnetic ground states and their properties.
• To provide a theoretical framework for recent experimental findings.

Main Methods:

• Theoretical modeling of spin-orbit coupled Mott insulators.
• Analysis of classical spin liquid models.
• Investigation of quantum fluctuations and their effect on magnetic degeneracy.

Main Results:

• Off-diagonal exchange anisotropy drives these materials into a classical spin liquid.
• This regime is characterized by infinite ground states and emergent Ising variables.
• Quantum fluctuations can either preserve degeneracy or select noncoplanar magnetic states.

Conclusions:

• The study reveals a new mechanism for achieving classical spin liquids in realistic materials.
• The findings offer a consistent explanation for the suppression of X-ray magnetic circular dichroism in β-Li_{2}IrO_{3} under pressure.
• The results are broadly applicable to 2D and 3D tricoordinated materials with bond-directional anisotropy.