Electrical magnetochiral effect induced by chiral spin fluctuations

Area of Science:

• Condensed matter physics
• Materials science
• Magnetism

Background:

• Chirality in matter leads to unique optical, electrical, and magnetic properties.
• Magnetic crystals exhibit chirality through antisymmetric exchange interactions, forming helical spin orders.
• The origin of magnetism-induced chirality in electron transport remains an area of fundamental research.

Purpose of the Study:

• To investigate the manifestation of chiral spin fluctuations in the electrical magnetochiral effect in the chiral magnet MnSi.
• To elucidate the role of asymmetric electron scattering by chiral spin fluctuations in this effect.
• To identify conditions under which prominent electrical magnetochiral signals appear.

Main Methods:

• Experimental investigation of the electrical magnetochiral effect in MnSi under varying temperature, magnetic field, and pressure.
• Analysis of electron scattering mechanisms influenced by chiral spin fluctuations.
• Characterization of spin dynamics near classical and quantum phase transitions.

Main Results:

• Chiral spin fluctuations in MnSi were found to directly cause the electrical magnetochiral effect, a nonreciprocal and nonlinear electrical response.
• Prominent signals were observed in the paramagnetic phase near the helical ordering temperature and in a low-temperature, high-pressure topological spin state.
• These regions correspond to significant thermal and quantum spin fluctuations near phase transitions.

Conclusions:

• Asymmetric electron scattering by chiral spin fluctuations is identified as the key mechanism for the electrical magnetochiral effect in MnSi.
• The study demonstrates a direct link between spin fluctuations and emergent electromagnetic phenomena in chiral magnets.
• This finding opens avenues for exploring novel electromagnetic functionalities in chiral magnetic materials.