[1
]Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa
50011, USA
[2
]Division of Materials Science & Engineering, Ames Laboratory, U.S. Department
of Energy, Ames, Iowa 50011, USA
[3
]Wolfson Center for Magnetics, Cardiff University, Cardiff CF24 3AA, United Kingdom
[4
]Institute of Physics, Polish Academy of Science, Warsaw 02-668, Poland
[5
]Department of Materials Science & Engineering, Iowa State University, Ames, Iowa
50011, USA