1. Physics and Astronomy, University of California, Irvine, CA 92697, USA.
2. Physics and Astronomy, University of California, Riverside, CA 92521, USA.
3. Western Digital, 5600 Great Oaks Parkway, San Jose, CA 95119, USA.
4. Departamento de Física, CEDENNA, FCFM, Universidad de Chile, Santiago, Chile.
5. Institute of Magnetism, National Academy of Sciences of Ukraine, Vernadsky Avenue 36B, Kyiv 03142, Ukraine.
6. National University of Science and Technology MISiS, Moscow 119049, Russian Federation.