Location: Bldg. 218, Rm. C020
Novel nanoscale magnetic properties are the basis of recent advances in a wide variety of technologies, ranging from data storage to magnetic sensors and magneto-electronics. Nanomagnetism also plays a critical role in the newly emerging field of spintronics. CNST researchers are developing the ability to image these magnetic nanostructures, primarily using a measurement technique developed at NIST called scanning electron microscopy with polarization analysis (SEMPA).
By measuring the electron spin polarization of secondary electrons in a scanning electron microscope, SEMPA can directly measure the direction and magnitude of the magnetization with high spatial resolution. Using multiple spin analyzers, SEMPA provides a 3-dimensional picture of the magnetization direction with 10 nm spatial resolution and 1 nm probing depth.
The SEMPA system is used to image the magnetic nanostructure in a wide variety of materials and devices. Current investigations include patterned thin films for magnetic logic and spintronics, depth-profiling graded magnetic recording media, voltage controlled magnetism using multiferroics and piezoelectrics, and magnetic multilayers used in superconductivity applications. Collaborations and external users are strongly encouraged.
Researchers in the nanomagnetic imaging lab work closely with two complimentary CNST nanomagnetic research areas: Nanomagnet Dynamics which is developing techniques to measure ultra-fast magnetization dynamics in magnetic nanostructures and Theory which provides modeling, theory, and simulations of nanoscale magnetic structure, dynamics, and carrier transport. An example of this collaboration is recent work on the use of spin-polarized currents to manipulate the magnetization in nanoscale magneto-electronics. In this case, SEMPA imaging revealed the structure and motion of domain walls in nanowires, spin-wave Doppler measurements revealed fundamentals of the current-magnetization interaction, and theory generated an understanding of spin torque switching that was used to both understand the measurements and to design functional magneto-electronic devices such as MRAM (Magnetic Random Access Memory). Together, these nanomagnetism research areas work to meet the goals of the CNST program in Future Electronics.