NMR

NMR is based on the interaction of the spin of a nucleus with the effective field present at the nucleus [35-
46]. Contrary to paramagnetic and diamagnetic materials, where the externally applied magnetic field is the
determining factor for the effective field, the hyperfine field is the dominating contribution in ferromagnetic
(spin polarised) materials. The hyperfine field refers to the (hyperfine) interaction of the nuclear magnetic
moment with magnetic fields originating in the spin and orbital currents of the surrounding electrons. The
hyperfine field is a sensitive probe of the local environments of the active nuclei due to the local
contributions to the hyperfine field, namely the transferred field which depends on the nearest and next
nearest neighbour atoms and their magnetic moments. This renders NMR an ideal method to study structural
properties of bulk samples as well as of thin films of spin polarised materials on a very local scale. Recent
results confirmed that NMR is a very suitable tool to reveal and quantify structural contributions and foreign
phases in spin polarised materials which are very difficult to detect with other methods like, e.g.,
conventional x-ray diffraction. In many cases, when the main group element is from the same period of the
periodic system as the transition metals, conventional x-ray or neutron diffraction may not provide enough
information determine the correct structure unambiguously. The NMR setup to measure the hyperfine field
and the corresponding resonance frequencies of ferromagnets is different from the common and
conventional setup [47] and requires different data analysis approaches and
data correction, e.g. for the enhancement factor [47].

 

[35] M. Wojcik, W. Van Roy, E. Jedryka, S. Nadolski, G. Borghs, and J. De Boeck. J. Magn. Magn.Mater.,
240, 414 (2002).
[36] W. Van Roy, M. Wojcik, E. Jedryka, S. Nadolski, D. Jalabert, B. Brijs, G. Borghs, and J. De Boeck.
Appl. Phys. Lett., 83, 4214 (2003).
[37] H. Wieldraaijer, W. J. M. de Jonge, and J. T. Kohlhepp. Phys. Rev. B, 72, 155409 (2005).
[38] H. Wieldraaijer, W. J. M. de Jonge, and J. T. Kohlhepp. J. Magn. Magn. Mater., 286, 390 (2005).
[39] M. Wojcik, E. Jedryka, I. Skorvanek, and P. Svec. J. Magn. Magn. Mater., 290-291, 1431 (2005).
[40] M. Wojcik, E. Jedryka, S. Nadolski, D. Rubi, C. Frontera, J. Fontcuberta, B. Jurca, N. Dragoe, and P.
Berthet. Phys. Rev. B, 71, 104410 (2005).
[41] M.Wojcik, E. Jedryka, I. Skorvanek, J. Marcin, and P. Svec. J. Magn. Magn. Mater., 304, e712 (2006).
[42] K. Inomata, S. Okamura, A. Miyazaki, N. Tezuka, M. Wojcik, and E. Jedryka. J. Phys. D: Appl. Phys.,
39, 816 (2006).
[43] K. Inomata, S. Okamura, A. Miyazaki, M. Kikuchi, N. Tezuka, M. Wójcik, and E. Jedryka, J. Phys. D:
Appl. Phys. 39, 816 (2006).
[44] S. Wurmehl, J. T. Kohlhepp, H. J. M. Swagten, B. Koopmans, M. Wójcik , B. Balke, C. G. F. Blum, V.
Ksenofontov, G. H. Fecher, C. Felser, Appl. Phys. Lett. 91 052506 (2007).
[45] S. Wurmehl, J. T. Kohlhepp, H. J. M. Swagten, B. Koopmans, J. Phys. D: Appl. Phys. 41 115007
(2008).
[46] S. Wurmehl, J. T. Kohlhepp, H. J. M. Swagten, B. Koopmans, C. G. F. Blum, V. Ksenofontov, H.
Schneider, G. Jakob, D. Ebke, G. Reiss, J. Phys. D: Appl. Phys. 42 084017 (2009).
[47] S. Wurmehl, J. T. Kohlhepp, Invited topical review J. Phys. D: Appl. Phys. 41, 173002 (2008).