Controlling the magnetic structure of Co/Pd thin films by direct laser interference patterning

Area of Science:

• Materials Science
• Nanotechnology
• Magnetism

Background:

• Magnetic thin films, such as [Co/Pd] multilayers, are crucial for data storage and spintronic devices.
• Controlling magnetic domain structures at the nanoscale is essential for advanced applications.
• Existing methods for nanostructure fabrication can be slow and costly.

Purpose of the Study:

• To develop a novel, parallel method for creating magnetic nanostructures using laser interference.
• To investigate the thermal effects of laser patterning on the magnetic properties of [Co/Pd] thin films.
• To demonstrate the fabrication of magnetic nanowire arrays with nanoscale dimensions.

Main Methods:

• Utilizing nanosecond pulsed two-beam laser interference to generate 2D temperature patterns on [Co/Pd] multilayer films.
• Inducing thermal demagnetization by exceeding the Curie temperature.
• Employing numerical simulations based on the Landau-Lifshitz-Bloch formalism to understand experimental observations.
• Characterizing the resulting magnetic domain structures and magnetization states.

Main Results:

• Laser interference successfully generated 2D temperature patterns, leading to drastic changes in the magnetic domain structure of [Co/Pd] films above the Curie temperature.
• Irreversible changes in the multilayer system were observed at higher temperatures, resulting in the loss of out-of-plane magnetization.
• Numerical simulations supported experimental findings, highlighting the role of defect sites and anisotropy changes.
• The method enabled the transfer of 1D temperature patterns into magnetic stripe patterns, producing magnetic nanowire arrays with ~100 nm lateral dimensions over several square millimeters.

Conclusions:

• Parallel direct laser interference patterning is a viable and efficient alternative to serial electron beam writing for fabricating magnetic nanostructures.
• This technique allows for the precise control and patterning of magnetic properties in thin films.
• The ability to create magnetic nanowire arrays opens possibilities for advanced magnetic device applications.