Thermoelectric detection of spin waves

Area of Science:

• Condensed Matter Physics
• Spintronics
• Thermodynamics

Background:

• Spin waves are fundamental excitations in magnetic materials, crucial for understanding magnetism and developing spintronic devices.
• Thermoelectric effects offer pathways for converting heat gradients into electrical signals, potentially enabling novel detection methods.

Purpose of the Study:

• To investigate the thermoelectric detection of spin waves in Permalloy (Py) stripes.
• To identify the underlying thermoelectric mechanism responsible for the detected voltage signal.

Main Methods:

• Excitation of spin waves in Permalloy stripes using a microwave current in a coplanar waveguide.
• Measurement of DC voltage along the Permalloy stripe using electrical contacts.
• Analysis of voltage signals as a function of applied magnetic field and microwave frequency.

Main Results:

• A distinct electrical voltage signature characteristic of spin wave excitations was observed with a high signal-to-noise ratio.
• The signal's symmetry with respect to the applied magnetic field confirmed the anomalous Nernst effect as the dominant mechanism.
• Seebeck effects, anisotropic magnetoresistance, and spin-motive forces were ruled out as primary contributors.

Conclusions:

• The anomalous Nernst effect provides an effective method for the thermoelectric detection of spin waves in Permalloy.
• Spin wave dissipation leads to local heating, creating a temperature gradient that drives the anomalous Nernst voltage.
• This work establishes a new technique for probing spin wave dynamics and their thermal properties.