Strong nonlinearity and hysteresis of Hall resistance versus magnetization in nickel thin films

The anomalous Hall effect (AHE) in ferromagnetic materials is perhaps one of the oldest unresolved mysteries in physics. First observed in 1881, its mechanism is still a controversial topic today. The question remains whether AHE is caused by intrinsic (Berry phase and band structure) or extrinsic (defect scattering) effects or a combination of both. Here we present experimental observation in nickel thin films that seems to add to the mystery, but may in fact provide crucial clues for ultimately resolving the controversy. The key observation is that the Hall resistivity of nickel films is a strongly nonlinear function of the magnetization and displays clear hysteresis with respect to M. Specifically, at low temperatures, the anomalous Hall coefficient switches between two saturated values under the magnetic field with a narrow transition region, but with a strong hysteresis, in contrast to the slow saturation of the magnetization. The nonlinearity and the hysteresis become more apparent with decreasing temperature or film thickness. Despite the simplicity of the lattice and magnetic structure of nickel films, these results are outside our current understanding of AHE, whether using intrinsic or extrinsic mechanisms of AHE. It presents a challenge for these models, and may be used as a test of validity for both types of theories.

[1]  P. Nozières,et al.  A simple theory of the anomalous hall effect in semiconductors , 1973 .

[2]  N. Rostoker,et al.  Hall Effect in Ferromagnetic Materials , 1953 .

[3]  M. Salamon,et al.  Magnetotransport in manganites and the role of quantal phases: theory and experiment. , 1999, Physical Review Letters.

[4]  Y Tokura,et al.  Crossover behavior of the anomalous Hall effect and anomalous nernst effect in itinerant ferromagnets. , 2007, Physical review letters.

[5]  G. White,et al.  Thermal expansion of germanium and silicon at low temperatures , 1965 .

[6]  Charles R. Westgate,et al.  The Hall effect and its applications , 1980 .

[7]  Naoto Nagaosa,et al.  Intrinsic versus extrinsic anomalous Hall effect in ferromagnets. , 2006, Physical review letters.

[8]  E. Pugh.  Hall Effect and the Magnetic Properties of Some Ferromagnetic Materials , 1930 .

[9]  N. Nagaosa,et al.  Spin Chirality, Berry Phase, and Anomalous Hall Effect in a Frustrated Ferromagnet , 2001, Science.

[10]  Enge Wang,et al.  First principles calculation of anomalous Hall conductivity in ferromagnetic bcc Fe. , 2003, Physical review letters.

[11]  Robert Karplus,et al.  Hall Effect in Ferromagnetics , 1954 .

[12]  Naoto Nagaosa,et al.  Topological Nature of Anomalous Hall Effect in Ferromagnets , 2002 .

[13]  V. Marsocci,et al.  Measurements of the Planar Hall Effect in Polycrystalline and in Single‐Crystal Nickel Thin Films , 1969 .

[14]  J. Smit.  The spontaneous hall effect in ferromagnetics II , 1955 .

[15]  A. Milner,et al.  Effect of surface scattering on the extraordinary Hall coefficient in ferromagnetic films , 2002 .

[16]  Y. Hoshino,et al.  Initial growth processes of ultra-thin Ni-layers on Si(111) and electronic structure of epitaxially grown NiSi2 , 2005 .

[17]  Qian Niu,et al.  Wave-packet dynamics in slowly perturbed crystals: Gradient corrections and Berry-phase effects , 1999 .

[18]  E. Hall,et al.  XVIII. On the “Rotational Coefficient” in nickel and cobalt , 1881 .

[19]  M. Scheffler,et al.  First-principles study of thin magnetic transition-metal silicide films on Si(001) , 2005, cond-mat/0504515.

[20]  Y. Tokura,et al.  Doping dependence of the anomalous Hall effect in La 1 − x Sr x Co O 3 , 2006 .

[21]  Kiyoyuki Terakura,et al.  The Anomalous Hall Effect and Magnetic Monopoles in Momentum Space , 2003, Science.

[22]  R. Cava,et al.  Dissipationless Anomalous Hall Current in the Ferromagnetic Spinel CuCr2Se4-xBrx , 2004, Science.

[23]  L. Berger,et al.  Side-Jump Mechanism for the Hall Effect of Ferromagnets , 1970 .

[24]  Berry Phase Theory of the Anomalous Hall Effect: Application to Colossal Magnetoresistance Manganites , 1999, cond-mat/9905007.