Significant Unconventional Anomalous Hall Effect in Heavy Metal/Antiferromagnetic Insulator Heterostructures

Area of Science:

• Condensed Matter Physics
• Quantum Transport Phenomena
• Spintronics

Background:

• The anomalous Hall effect (AHE) typically vanishes at high temperatures due to thermal dephasing.
• The survival of AHE at high temperatures in heavy metal (HM)/antiferromagnetic insulator (AFMI) heterostructures is puzzling.
• Conventional understanding suggests AHE diminishes with increasing temperature, contrary to observations in specific HM/AFMI systems.

Purpose of the Study:

• To investigate the unconventional high-temperature AHE observed in HM/AFMI heterostructures.
• To elucidate the mechanism behind the AHE's persistence at elevated temperatures around the Néel temperature.
• To explore the role of spin texture and topological charge in high-temperature AHE.

Main Methods:

• Experimental observation of AHE in HM/AFMI heterostructures.
• Measurement of anomalous Hall resistivity around the Néel temperature.
• Atomistic spin dynamics simulations to model spin texture formation.

Main Results:

• An unconventional high-temperature AHE was observed in HM/AFMI heterostructures, specifically around the Néel temperature.
• Anomalous Hall resistivity reached up to 40 nΩ cm.
• The AHE is attributed to a noncollinear antiferromagnetic (AFM) spin texture with a non-zero net topological charge.

Conclusions:

• A novel mechanism for high-temperature AHE in HM/AFMI systems is identified.
• The emergence of a noncollinear AFM spin texture, stabilized by interfacial interactions and thermal fluctuations, is crucial for the observed AHE.
• This finding challenges conventional understanding of AHE temperature dependence and opens new avenues in spintronics research.