Coherent Spin Pumping Originated from Sub-Terahertz Néel Vector Dynamics in Easy Plane α-Fe_{2}O_{3}/Pt.

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Spin-to-charge current interconversion is crucial for spintronic devices.
• Understanding spin pumping in antiferromagnets is key for novel functionalities.
• Hematite (α-Fe_{2}O_{3}) is an important material for studying antiferromagnetic spintronics.

Purpose of the Study:

• To investigate spin-to-charge current interconversion in (0001) α-Fe_{2}O_{3}/Pt heterostructures.
• To explore spin pumping mechanisms from quasiferromagnetic and quasiantiferromagnetic (q-AFM) modes.
• To determine the role of microwave magnetic field orientation and Néel vector dynamics.

Main Methods:

• All-optical polarization-controlled microwave excitation at subterahertz frequencies.
• Experimental study on bulk and thin film α-Fe_{2}O_{3}/Pt heterostructures.
• Analysis of spin pumping based on relative orientation of microwave field and magnetic moment.

Main Results:

• Coherent spin pumping observed from both quasiferromagnetic and q-AFM modes.
• Spin pumping from q-AFM mode is enabled only when the microwave field is parallel to the magnetic moment.
• Experimental determination of spin-mixing conductance components, challenging previous interpretations.
• Observed vanishing of q-AFM spin pumping in thin films.

Conclusions:

• Néel vector dynamics significantly contribute to spin pumping in easy-plane antiferromagnets.
• The study clarifies spin pumping mechanisms in hematite and its heterostructures.
• Results provide insights into factors affecting spin pumping in thin films, such as inhomogeneities and thickness.