Correlation of Exchange Bias and Angle on Applied Perturbation Field and Anti-Ferromagnetic Spins

Xinwen Fu, Guixin Cao, Yuze Gao, Zhiwei Wu, Jincang Zhang

.

DOI: 10.4236/jmp.2011.210148                

Abstract

High-resolution anisotropic magneto-resistance measurement (AMR) was used to detailed study the training effect in exchange biased CoO/Co bi-layer. The sample was cooled to 10 K from room temperature in the magnetic cooling field of 4000 Oe. Then we used 1500 Oe declined perturbation field to pin the magnetization orientation of the FM layer. The perturbation field forms certain angle Θ with the cooling field direction in-plane to re-induce the untrained state. The dependence of the untrained state on the angle between the direction of perturbation field and cooling field has been investigated. The AMR results reveal that the re-induced degree of untrained state is strongly correlated to the angle Θ. The exchange bias field HE for different Θ has been determined from the AMR results, which is in apparent agreement with the Meiklejohn-Bean model. The recover degree of untrained state is the largest when the angle is 75°, which is different from the traditional view point that untrained state should be the maximum when it is perpendicular. The training effect is related to the FM spin orientation, which can induce the change of the interfacial AFM spin reorientation with different angles.

Keywords

Natural Asset, Financial Value, Neural Network

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	W. H. Meiklejohn and C. P. Bean, “New Magnetic Anisotropy,” Physical Review, Vol. 105, No. 3, 1957, pp. 904-913. doi:10.1103/PhysRev.105.904
[2]	B. Dieny, V. S. Speriosu, S. S. P. Parkin, B. A. Gurney, D. R. Wilhoit and D. Mauri, “Giant Magnetoresistive in Soft Ferromagnetic Multilayers,” Physical Review B, Vol. 43, No. 1, 1991, pp. 1297-1300. doi:10.1103/PhysRevB.43.1297
[3]	S. Brems, K. Temst and C. V. Haesendonck, “Origin of the Training Effect and Asymmetry of the Magnetization in Polycrystalline Exchange Bias System,” Physical Review Letters, Vol. 99, 2007, pp. 067201(4).
[4]	J. Nogués and I. K. Schuller,“Exchange Bias,” Journal of Magnetism and Magnetic Materials, Vol. 192, No. 2, 1999, pp. 203-232. doi:10.1016/S0304-8853(98)00266-2
[5]	A. E. Berkowitz and K. Takano, “Exchange Anisotropy —A Review,” Journal of Magnetism and Magnetic Materials, Vol. 200, No. 1, 1999, pp. 552-570. doi:10.1016/S0304-8853(99)00453-9
[6]	R. L. Stamps, “Mechanisms for Exchange Bias,” Journal of Physics D, Vol. 33, 2000, pp. R247-268. doi:10.1088/0022-3727/33/23/201
[7]	M. Kiwi, “Exchange Bias Theory,” Journal of Magnetism and Magnetic Materials, Vol. 234, No. 3, 2001, pp. 584-595. doi:10.1016/S0304-8853(01)00421-8
[8]	S. Brems, D. Buntinx, K. Temst, C. V. Haesendonck, F. Radu and H. Zabel, “Reversing the Training Effect in Exchange Biasd CoO/Co Blayers,” Physical Review Letters, Vol. 95, 2005, pp. 157202(4).
[9]	S. Brems, A. Volodin, C. V. Haesendonck and K. Temst, “Magnetic Force Microscopy Study of the Training Effect in Polycrystalline Co/CoO Bilayers,” Journal of Applied Physics, Vol. 103, 2008, pp. 113912(4).
[10]	T. Hauet, J. A. Borchers, Ph. Mangin, Y. Henry and S. Mangin, “Training Effect in an Exchange Bias System: The role of Interfacial Domain Walls,” Physical Review Letters, Vol. 96, 2006, pp. 067207(4).
[11]	T. Gredig, L. N. Krivorotov and E. Dan. Dahlberg, “Magnetization Reversal in Exchange Biased Co/CoO Probed with Anisotropic Magnetoresistance,” Journal of Applied Physics, Vol. 91, 2002, pp. 7760-7763. doi:10.1063/1.1447181
[12]	S. Polisetty, S. Sahoo and C. Binek, “Scaling Behavior of the Exchange—Bias Training Effect,” Physical Review B, 76, 2007, pp. 184423(9).
[13]	K. Zhang, T. Zhao and H. Fujiwara, “Training Effect of Exchange Biased Iron-Oxide/Ferromagnet Systems,” Journal of Applied Physics, Vol. 89, No. 11, 2001, pp. 6910-6912. doi:10.1063/1.1360682
[14]	P. Y. Yang, C. Song, F. Zeng and F. Pan, “Tuning the Training Effect in Exchange Biased NiO/Ni Bilayers,” Applied Physics Letters, Vol. 92, 2008, pp. 243113(3).
[15]	A. Hoffmann, “Symmetry Driven Irreversibilities at Ferromagnetic-Antiferromagnetic Interfaces,” Physical Review Letters, Vol. 93, 2004, pp. 097203(4).
[16]	M. Kiwi, J. Mejía-López, R. D. Portugal and R. Ramírez, “Exchange-Bias Systems with Compensated Interfaces,” Applied Physics Letters, Vol. 75, 1999, pp. 3995-3997. doi:10.1063/1.125517
[17]	C. L. Chien, V. S. Gornakov, V. I. Nikitenko, A. J. Shapiro and R. D. Shull, “Hybrid Domain Walls and Antiferromagnetic Domains in Exchange-Coupled Ferromagnet/Antiferromagnet Bilayers,” Physical Review B, Vol. 68, 2003, pp. 014418(5).
[18]	M. Gruyters and D. Riegel, “Strong Exchange Bias by a Single Layer of Independent Antiferromagnetic Grains: The CoO/Co Model System,” Physical Review B, Vol. 63, 2000, pp. 052401(4).
[19]	T. Hauet, S. Mangin, J. McCord, F. Montaigne and E. E. Fullerton, “Exchange-Bias Training Effect in TbFe/GdFe: Micromagnetic Mechanism,” Physical Review B, Vol. 76, 2007, pp. 144423(5).
[20]	W. H. Meiklejohn, “Exchange Anisotropy—A Review,” Journal of Applied Physics, Vol. 33, 1962, pp. 1328-1335. doi:10.1063/1.1728716
[21]	Ch. Binek, A. Hochstrat, and W. Kleemann, “Exchange Bias in a Generalized Meiklejohn-Bean Approach,” Journal of Magnetism and Magnetic Materials, Vol. 234, 2001, pp. 354-358.
[22]	F. Y. Yang, and C. L. Chien, “Spiraling Spin Structure in an Exchange-Coupled Antiferromagnetic Layer,” Physical Review Letters, Vol. 85, No. 12, 2000, pp. 2597-2600. doi:10.1103/PhysRevLett.85.2597
[23]	A. L. Kobrinskii, A. M. Goldman, M. Varela and S. J. Pennycook, “Thickness Dependence of the Exchange Bias in Epitaxial Manganite Bilayers,” Physical Review B, Vol. 79, 2009, pp. 094405(7).
[24]	S. Chikazumi, “Physics of Ferromagnetism,” Oxford University Press, New York, 1997, p. 329.
[25]	C. Hou, H. Fujiwara and F. Ueda, “Effect of F/AF Coupling Strength on the Magnetization Process of F/AF System,” Journal of Magnetism and Magnetic Materials, Vol. 198, No. 1-3, 1999, pp. 450-452. doi:10.1016/S0304-8853(98)01165-2
[26]	E. Fulcomer and S. H. Charap, “Thermal Fluctuation Aftereffect Model for Some Systems with Ferromagnetic- Antiferromagnetic Coupling,” Journal of Applied Physics, Vol. 43, 1972, pp. 4190-4199. doi:10.1063/1.1660894