Spin freezing in geometrically frustrated antiferromagnets with weak disorder

Area of Science:

• Condensed Matter Physics
• Magnetism
• Disordered Systems

Background:

• Geometrically frustrated magnets exhibit complex magnetic behavior due to competing interactions.
• The pyrochlore lattice is a prime example of a geometrically frustrated system.
• Understanding the role of disorder is crucial for explaining experimental observations in these materials.

Purpose of the Study:

• To investigate the impact of weak exchange interaction disorder on geometrically frustrated antiferromagnets.
• To model the low-temperature behavior of the classical Heisenberg antiferromagnet on the pyrochlore lattice with disorder.
• To determine if disorder can explain the spin freezing phenomenon in these systems.

Main Methods:

• Utilized a classical Heisenberg antiferromagnet model with nearest-neighbor exchange on the pyrochlore lattice.
• Examined low-temperature behavior under conditions of weak disorder in exchange interaction strength.
• Employed Monte Carlo simulations to analyze system dynamics and phase transitions.

Main Results:

• Spatial modulation of exchange interactions was shown to generate long-range effective interactions.
• These interactions occur within the degenerate ground states of the clean system.
• A spin glass transition was identified at a temperature dependent on the disorder strength.

Conclusions:

• Weak disorder in exchange interactions can induce significant changes in the magnetic properties of frustrated systems.
• The observed spin glass transition and associated spin freezing are potentially explained by disorder-induced effects.
• Random strains and magnetoelastic coupling are identified as plausible sources of such disorder in real materials.