Enhanced spin Seebeck effect via oxygen manipulation

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• The Spin Seebeck effect (SSE) generates voltage from temperature gradients using magnons.
• SSE is promising for thermoelectric devices due to its simple geometry for waste heat harvesting.
• Current SSE applications are limited by low thermoelectric conversion efficiency.

Purpose of the Study:

• To investigate methods for enhancing the thermoelectric conversion efficiency of the Spin Seebeck effect.
• To explore the impact of interfacial oxidation on SSE performance in normal metal/ferromagnet/oxide structures.

Main Methods:

• Fabrication of W/CoFeB/AlOx thin-film structures.
• Utilizing voltage-induced interfacial oxidation of the CoFeB layer.
• Measuring the thermoelectric signal generated via SSE.

Main Results:

• Interfacial oxidation of CoFeB substantially enhanced the SSE signal by an order of magnitude.
• The enhancement mechanism involves a reduced exchange interaction in the oxidized ferromagnet.
• This leads to an increased temperature difference between magnons and electrons and/or a magnon chemical potential gradient.

Conclusions:

• Interfacial oxidation is a viable strategy to significantly improve SSE thermoelectric conversion efficiency.
• The findings provide a promising pathway for developing more efficient thermoelectric devices based on SSE.
• This research is expected to stimulate further investigation into optimizing SSE for practical applications.