Defect-tuning exchange bias of ferromagnet/antiferromagnet core/shell nanoparticles by numerical study

The influence of non-magnetic defects on the exchange bias (EB) of ferromagnet (FM)/antiferromagnet (AFM) core/shell nanoparticles is studied by Monte Carlo simulations. It is found that the EB can be tuned by defects in different positions. Defects at both the AFM and FM interfaces reduce the EB field while they enhance the coercive field by decreasing the effective interface coupling. However, the EB field and the coercive field show respectively a non-monotonic and a monotonic dependence on the defect concentration when the defects are located inside the AFM shell, indicating a similar microscopic mechanism to that proposed in the domain state model. These results suggest a way to optimize the EB effect for applications.

[1]  Y. Kudasov,et al.  Frustrated lattices of Ising chains , 2012 .

[2]  Shouheng Sun,et al.  Tuning exchange bias in core/shell FeO/Fe3O4 nanoparticles. , 2012, Nano letters.

[3]  S. Valeri,et al.  Structure and stability of nickel/nickel oxide core–shell nanoparticles , 2011, Journal of physics. Condensed matter : an Institute of Physics journal.

[4]  U. Nowak,et al.  Atomistic spin model based on a spin-cluster expansion technique: Application to the IrMn3/Co interface , 2010, 1010.2375.

[5]  R. Stamps,et al.  Exchange bias: Dependence on the properties of the ferromagnetic interface layer , 2010 .

[6]  M. Feygenson,et al.  Controlling the exchange bias field in Co core/CoO shell nanoparticles , 2010 .

[7]  J. Borchers,et al.  Core-shell magnetic morphology of structurally uniform magnetite nanoparticles. , 2010, Physical review letters.

[8]  U. Nowak,et al.  Exchange bias for a ferromagnetic film coupled to a spin glass , 2009 .

[9]  G. Salazar-Alvarez,et al.  Magnetic proximity effect features in antiferromagnetic/ferrimagnetic core-shell nanoparticles. , 2009, Physical review letters.

[10]  Karen Willcox,et al.  Kinetics and kinematics for translational motions in microgravity during parabolic flight. , 2009, Aviation, space, and environmental medicine.

[11]  K. Trohidou,et al.  Numerical study of the exchange-bias effect in nanoparticles with ferromagnetic core/ferrimagnetic disordered shell morphology , 2009 .

[12]  H. Zabel,et al.  Tuning the exchange bias by using Cr interfacial dusting layers , 2008 .

[13]  M. Kim,et al.  Manipulating the magnetic structure of Co core/CoO shell nanoparticles: implications for controlling the exchange bias. , 2008, Physical review letters.

[14]  K. Trohidou,et al.  Surface effects on the magnetic behaviour of nanoparticles with core/shell morphology , 2008 .

[15]  C. Prieto,et al.  Magnetic properties and interaction mechanisms of iron-based core–shell structures prepared by sputtering at low substrate temperatures , 2008 .

[16]  C. Marrows,et al.  Controlled enhancement or suppression of exchange biasing using impurity δ layers , 2007, 0708.0375.

[17]  Ò. Iglesias,et al.  Modelling exchange bias in core/shell nanoparticles , 2007, Journal of physics. Condensed matter : an Institute of Physics journal.

[18]  D. Fiorani,et al.  Exchange bias in disordered granular systems , 2007 .

[19]  H. Zabel,et al.  Exchange Bias Effect of Ferro-/Antiferromagnetic Heterostructures , 2007, 0705.2055.

[20]  M. Bawendi,et al.  Defects in CoO in oxidized cobalt nanoparticles dominate exchange biasing and exhibit anomalous magnetic properties , 2006 .

[21]  J. Sort,et al.  Shell-driven magnetic stability in core-shell nanoparticles. , 2006, Physical review letters.

[22]  J. González,et al.  Exchange bias and nanoparticle magnetic stability in Co-CoO composites , 2006 .

[23]  Jordi Sort,et al.  Exchange bias in nanostructures , 2005 .

[24]  Ò. Iglesias,et al.  Microscopic origin of exchange bias in core/shell nanoparticles , 2005, cond-mat/0509553.

[25]  M. Bawendi,et al.  Exchange biasing and magnetic properties of partially and fully oxidized colloidal cobalt nanoparticles , 2005 .

[26]  K. Trohidou,et al.  Numerical study of the exchange bias effects in magnetic nanoparticles with core/shell morphology , 2005 .

[27]  Dominique Givord,et al.  Beating the superparamagnetic limit with exchange bias , 2003, Nature.

[28]  U. Nowak,et al.  Domain state model for exchange bias. II. Experiments , 2002 .

[29]  U. Nowak,et al.  Domain state model for exchange bias. I. Theory , 2002 .

[30]  Miguel Kiwi,et al.  Exchange bias theory , 2001 .

[31]  Porto,et al.  Influence of dipolar interaction on magnetic properties of ultrafine ferromagnetic particles , 2000, Physical review letters.

[32]  Dimitrov,et al.  Magnetic properties of superparamagnetic particles by a Monte Carlo method. , 1996, Physical review. B, Condensed matter.

[33]  C. Foiles,et al.  Antiferromagnetic spin-glass , 1982 .

[34]  N. Metropolis,et al.  Equation of State Calculations by Fast Computing Machines , 1953, Resonance.

[35]  Mannan Ali,et al.  Exchange bias using a spin glass. , 2007, Nature materials.