Bolometer detection of magnetic resonances in nanoscaled objects

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Probing spin dynamics in nanosized magnetic materials requires highly sensitive detection methods.
• Dissipative damping of spin waves is crucial for understanding energy loss in magnetic nanostructures.
• Existing thermal detection methods often lack the sensitivity needed for nanoscale spin dynamics.

Purpose of the Study:

• To develop and characterize a nanoscaled thermocouple (ThC) as a temperature sensor for a highly sensitive bolometer.
• To utilize the bolometer for probing the dissipative damping of spin dynamics in nanosized Permalloy (Py) stripes.
• To demonstrate the capability of the ThC-based bolometer in detecting temperature changes and spin waves.

Main Methods:

• Fabrication of an Au-Pd ThC device using electron beam lithography on a silicon nitride membrane.
• Utilizing the ThC as a temperature sensor integrated with a bolometer to measure microwave absorption by Py stripes.
• Employing a 3D finite element method to estimate absorbed microwave power and analyze heat dissipation.

Main Results:

• The ThC-based bolometer achieved a voltage responsivity of 15 V W⁻¹ and a noise equivalent power of 3 nW Hz⁻¹/².
• The device detected temperature changes on the order of a few mK due to resonant microwave absorption.
• Standing spin waves with different mode numbers were successfully detected, demonstrating high sensitivity.

Conclusions:

• The nanoscaled thermocouple serves as an effective temperature sensor for a sensitive bolometer, enabling the study of spin dynamics.
• Silicon nitride membranes are crucial for minimizing heat dissipation, facilitating accurate thermal detection of spin dynamics.
• The ThC device offers excellent magnetic resonance response and temperature resolution for nanoscale spin physics investigations.