Magnetic Properties of Proton Irradiated Giant Magnetoresistance Multilayers

doi:10.3724/SP.J.1077.2013.13523

Abstract

Abstract:

The magnetic properties of proton irradiated CoFe/(CoFe/Cu)₁₀/CoFe/Ta giant magnetoresistance multilayers (GMR-MLs) were investigated experimentally and theoretically. GMR-MLs were prepared by magnetron sputtering and exposed to 5 MeV proton beam with a series of radiation fluences and fluence rates. X-ray diffraction indicated that the crystal structures of CoFe/Cu were unaffected after irradiation. The saturation magnetization and intrinsic resistance increased monotonically with the increase of the radiation fluence and fluence rate. The value of MR in the irradiated samples decreased slightly with the radiation fluence, which was mainly explained by the two spin- related conductivity channel model.

Key words: giant magnetoresistance, proton irradiation, spin-related scattering, two spin-related conductivity channel

YIN Cong, XIE Dan, XU Jian-Long, REN Tian-Ling. Magnetic Properties of Proton Irradiated Giant Magnetoresistance Multilayers[J]. Journal of Inorganic Materials, 2014, 29(3): 331-336.

Figures/Tables 7

Table 1 The proton irradiation conditions of different GMR-ML samples

Sample	Radiation fluence /(p·cm^-2)	Fluence rate /(p·cm^-2·s^-1)	Radiation time/s
S0	0	0	0
S1	10¹¹	~10⁸	988
S2	10¹²	~6×10⁸	1724
S3	10¹³	~10⁹	10208
S4	10¹¹	~8.8×10⁶	11351
S5	10¹¹	~10⁹	98

Fig. 1 Refined XRD patterns of GMR-ML samples before and after the proton irradiation at room temperature

Fig. 2 M-H curves of GMR-ML samples before and after proton irradiation at room temperature with different radiation fluences (a) and fluence rates (b)

Table 2 Results of refined parameters of proton irradiated GMR-ML samples at room temperature

Sample	M_S/(×10³, kA·m^-1)	H_C/(kA·m^-1)	R₀/Ω	MR/%
S0	1.8071	3.1682	1.9944	8.06
S1	1.8832	3.0882	1.8795	7.594
S2	1.8855	3.0792	1.8805	7.145
S3	1.9252	3.0206	6.4529	6.167
S4	1.8743	2.7296	1.3677	8.027
S5	2.0329	3.1112	2.8604	7.717

Fig. 3 Radiation fluence dependence of (a) the saturation magnetization & coercive field and (b) the intrinsic resistance & magnetoresistance ratio in proton irradiated GMR-ML samples at room temperature. The inset of (a) is the fluence rate dependence of MS and HC

Fig. 4 Magnetoresistance ratio versus the magnetic field of GMR-ML samples before and after proton irradiation at room temperature with different radiation fluences (a) and fluence rates (b)

Table 3 Calculation results of R↑ and R↓ in different GMR-ML samples

Sample	R_↑/Ω	[ΔR_↑/R_↑(S0)] /%	R_↓/Ω	[ΔR_↓/R_↓(S0)] /%
S0	0.2840	0	0.4983	0
S1	0.2704	-4.79%	0.4646	-6.76%
S2	0.2723	-4.12%	0.4590	-7.89%
S3	0.9438	2.32	1.5483	2.11
S4	0.1956	-31.13%	0.3429	-31.19%
S5	0.4100	44.37%	0.7107	42.62%

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