Evidence of random magnetic anisotropy in ferrihydrite nanoparticles based on analysis of statistical distributions

We show that the magnetic anisotropy energy of antiferromagnetic ferrihydrite depends on the square root of the nanoparticles' volume, using a method based on the analysis of statistical distributions. The size distribution was obtained by transmission electron microscopy, and the anisotropy energy distributions were obtained from ac magnetic susceptibility and magnetic relaxation. The square root dependence corresponds to random local anisotropy, whose average is given by its variance, and can be understood in terms of the recently proposed single phase homogeneous structure of ferrihydrite.

[1]  I. Barakat.  Pierre , 2009 .

[2]  M. Schoonen,et al.  The Structure of Ferrihydrite, a Nanocrystalline Material , 2007, Science.

[3]  M. Shliomis,et al.  Theory of the Dynamic Susceptibility of Magnetic Fluids , 2007 .

[4]  E. Beaurepaire,et al.  Optical in situ size determination of single lanthanide-ion doped oxide nanoparticles , 2006 .

[5]  M. F. Hansen,et al.  On the interpretation of magnetization data for antiferromagnetic nanoparticles , 2006 .

[6]  H. Kachkachi.  Effects of spin non-collinearities in magnetic nanoparticles , 2006, cond-mat/0609606.

[7]  L. Liz‐Marzán,et al.  Structural and magnetic studies in ferrihydrite nanoparticles formed within organic-inorganic hybrid matrices , 2006 .

[8]  L. Carlos,et al.  Relevance of magnetic moment distribution and scaling law methods to study the magnetic behavior of antiferromagnetic nanoparticles: Application to ferritin , 2004, cond-mat/0408134.

[9]  T. Cren,et al.  The remarkable difference between surface and step atoms in the magnetic anisotropy of two-dimensional nanostructures , 2003, Nature materials.

[10]  V. Bermudez,et al.  Magnetic properties of Fe-doped organic–inorganic nanohybrids , 2003 .

[11]  P. Allen,et al.  Apparent magnetic energy-barrier distribution in horse-spleen ferritin : Evidence for multiple interacting magnetic entities per ferrihydrite nanoparticle , 2001 .

[12]  A. Vaurès,et al.  Enhancement of the magnetic anisotropy of nanometer-sized Co clusters: Influence of the surface and of interparticle interactions , 2001, cond-mat/0108304.

[13]  J. M. Cowley,et al.  Structure of synthetic 6-line ferrihydrite by electron nanodiffraction , 2001 .

[14]  S. Mann,et al.  Non-Langevin behaviour of the uncompensated magnetization in nanoparticles of artificial ferritin , 2000 .

[15]  J. Dormann,et al.  From pure superparamagnetism to glass collective state in γ-Fe2O3 nanoparticle assemblies , 1999 .

[16]  J. Tejada,et al.  Resonant spin tunneling in small antiferromagnetic particles , 1999 .

[17]  D. Awschalom,et al.  Excess spin and the dynamics of antiferromagnetic ferritin , 1999, cond-mat/9904051.

[18]  J. Jambor,et al.  Occurrence and Constitution of Natural and Synthetic Ferrihydrite, a Widespread Iron Oxyhydroxide. , 1998, Chemical reviews.

[19]  A. Berkowitz,et al.  MAGNETIC HYSTERESIS ANOMALIES IN FERRITIN , 1997 .

[20]  P. Svedlindh,et al.  Intra-potential-well contribution to the AC susceptibility of a noninteracting nano-sized magnetic particle system , 1997 .

[21]  P. Nordblad,et al.  Energy barrier distribution of a noninteracting nano-sized magnetic particle system , 1997 .

[22]  Feng,et al.  Surface-induced superparamagnetic relaxation in nanoscale ferrihydrite particles. , 1996, Physical review. B, Condensed matter.

[23]  Dormann,et al.  Thermal variation of the relaxation time of the magnetic moment of gamma -Fe2O3 nanoparticles with interparticle interactions of various strengths. , 1996, Physical review. B, Condensed matter.

[24]  L. Balcells,et al.  T ln( {t}/{τ 0 }) scaling in small-particle systems: low-temperature behaviour , 1995 .

[25]  B. Barbara,et al.  Effects of the distribution of energy barriers on the magnetic relaxation of Ba-ferrite small particles at low temperatures , 1995 .

[26]  Iglesias,et al.  Magnetic relaxation in small-particle systems: ln(t/ tau 0) scaling. , 1993, Physical review. B, Condensed matter.

[27]  Q. Pankhurst,et al.  The inadequacy of applied-field Mossbauer spectroscopy as a means of proving the existence of speromagnetism , 1993 .

[28]  V. Drits,et al.  Local Structure of Ferrihydrite and Feroxyhite by Exafs Spectroscopy , 1993, Clay Minerals.

[29]  V. Drits,et al.  Structural Model for Ferrihydrite , 1993, Clay Minerals.

[30]  M. Shliomis,et al.  Frequency dependence and long time relaxation of the susceptibility of the magnetic fluids , 1993 .

[31]  R. Fitzpatrick,et al.  New Data and a Revised Structural Model for Ferrihydrite , 1988 .

[32]  E. Crow,et al.  Lognormal Distributions: Theory and Applications , 1987 .

[33]  Louis E. Brus,et al.  Electronic wave functions in semiconductor clusters: experiment and theory , 1986 .

[34]  Tarald O. Kvålseth,et al.  Some informational properties of the lognormal distribution , 1982, IEEE Trans. Inf. Theory.

[35]  P. Svedlindh,et al.  Measurement of complex susceptibility on a metallic spin glass with broad relaxation spectrum , 1981 .

[36]  R. Stephenson.  A and V , 1962, The British journal of ophthalmology.

[37]  R. Street,et al.  A Study of Magnetic Viscosity , 1949 .

[38]  M. F. Hansen,et al.  Magnetic Properties of Nanoparticles of Antiferromagnetic Materials , 2002 .