Pressure-induced colossal magnetocaloric effect in MnAs.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Thermodynamics

Background:

• The magnetocaloric effect (MCE) is crucial for magnetic refrigeration technologies.
• Previous MCE records at room temperature were limited, with Manganese Arsenide (MnAs) showing 40 J/(kg K) for a 5 T field change.
• Understanding the factors influencing MCE is key to developing more efficient cooling materials.

Purpose of the Study:

• To investigate colossal magnetocaloric effect (MCE) in MnAs under applied pressure.
• To explore the underlying mechanisms responsible for enhanced MCE beyond conventional magnetic contributions.
• To determine if magnetoelastic coupling influences lattice entropy variation in MnAs.

Main Methods:

• Measurements of magnetocaloric effect (MCE) on MnAs were conducted under varying pressure conditions.
• Analysis of entropy variation contributions, including lattice and electronic components, was performed.
• Investigation of magnetoelastic coupling's role in the observed MCE was a key focus.

Main Results:

• Colossal MCE values up to 267 J/(kg K) were achieved in MnAs under pressure, significantly exceeding previous benchmarks.
• The observed MCE surpassed the theoretical magnetic limit, indicating contributions beyond magnetic field independence.
• Evidence points to lattice entropy variation, mediated by magnetoelastic coupling, as the origin of the enhanced effect.

Conclusions:

• Applied pressure dramatically enhances the magnetocaloric effect in MnAs.
• Magnetoelastic coupling plays a critical role in driving colossal MCE by influencing lattice entropy.
• These findings open new avenues for designing advanced magnetocaloric materials for efficient cooling applications.