Saturated and Anisotropic Magnetostriction in an Altermagnet.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Magnetostriction, the strain in magnetic materials due to magnetic fields, is well-studied in ferromagnets.
• Antiferromagnetic (AFM) magnetostriction is typically nonsaturating and less understood.
• Altermagnets, a class of collinear AFMs with unique symmetries, are emerging materials.

Purpose of the Study:

• To investigate magnetostriction in the prototypical altermagnet, manganese telluride (MnTe).
• To characterize the magnetic-field dependence and symmetry of magnetostriction in MnTe.
• To elucidate the underlying physical mechanisms responsible for the observed magnetostriction.

Main Methods:

• Growth of high-quality single crystals of MnTe.
• Experimental measurement of magnetostriction under varying magnetic fields.
• First-principles calculations to model the strain-Néel order parameter coupling.

Main Results:

• Observed easily saturated magnetostriction in MnTe under a moderate magnetic field (∼0.7 T).
• The magnetostriction exhibits a distinct 2-fold symmetry anisotropy.
• Calculations confirm that symmetry-allowed coupling between elastic strain and the Néel order parameter drives these effects.

Conclusions:

• MnTe demonstrates a unique, saturable, and anisotropic magnetostriction, challenging conventional understanding of antiferromagnetic magnetostriction.
• The findings highlight the potential of altermagnets for novel magneto-mechanical applications.
• This work provides fundamental insights into the interplay between magnetism, mechanics, and crystal symmetry in altermagnets.