Achieving reliability during nanoscale fabrication of magnetic materials and related devices for ultrafast magnetic applications is a complex, lengthy and expensive process that requires access to the time-resolved response of magnetic properties. This is only available in a small number of specialized laboratories. On the other hand, industrial demands are for large scale production tools that do not sacrifice sample integrity and need to employ efficient techniques for nondestructive magnetic characterization with high spatial resolution. This is needed to improve fabrication throughput and minimize costs. Optical magnetometers provide high spatial resolution, although the ones in use today are only measuring either static magnetic properties or offer very modest temporal characterization capabilities.
Researchers at the University of Michigan have developed a new optical technique for ultrafast magnetometry based on pump-probe techniques, to provide detailed data on the temporal dynamics of magnetic properties. A new instrument apparatus with high spatial and temporal resolution has been built and tested to confirm applicability for nondestructive magnetic characterization. Component resolved magnetization dynamics is monitored as a function of time delay following fs optical pulse excitation. Determination of magnetic anisotropy, saturation magnetization, anisotropic magnetization relaxation rates in external magnetic field and time-resolved hysterezis was confirmed in thin film samples. Complimentary measurements of thermal and mechanical properties were demonstrated using the same apparatus prototype. Specific examples include determination of thin film thermal conductivity, film-substrate thermal boundary resistance and thin film thickness. The need of simultaneous knowledge of the thermal material properties is anticipated for the case of modern magnetic random access memories that use high currents for magnetic switching and operate at large transient temperatures, and also in cases where the device thermal management is very important.
Applications and Advantages
- Magnetometry of ultrathin films >2 nm
- Large-size specimen magneto-optical dynamics and thermal property mapping with 100 nm size)
- Uses small footprint fiber lasers, portable and compact
- In-situ capability for real-time monitor of material fabrication
- Accurate characterization of time-resolved magnetic, thermal and acoustic properties
- Technique can be customized to specific needs