Abstract

The influence of Ar-ion irradiation on the microstructure, interlayer coupling and giant magnetoresistance (GMR) effect in the model Fe/Cr system was studied by the conversion electron Mössbauer spectrometry (CEMS), vibrating sample magnetometry (VSM), and magnetoresistivity, for the Fe-1.4 nm/Cr-t_Cr multilayers with t_Cr ranging from 0.73 to 1.85 nm. The loss of antiferromagnetic coupling and the simultaneous degradation of GMR, observed for increasing ion dose, was caused by the formation of pinholes due to the increase of interface roughness and at high ion doses, by the ion-beam mixing leading to the alloying of Fe and Cr at interfaces.

Keywords: Ion irradiation; Mössbauer spectroscopy; Giant magnetoresistance; Interlayer coupling; Fe/cr multilayers

PACS: 68.35.−p; 75.47.De; 75.70.Cn; 76.80.+y

Article Outline

1. Introduction

2. Experiment

3. Results and discussion

References

(43K)
Fig. 1. CEMS spectra recorded for Fe(1.4 nm)/Cr(1.4 nm) multilayers in the as-deposited state (a) and after ion irradiation with doses indicated (b–d).

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Fig. 2. Hysteresis loops and GMR(H) dependencies for as-deposited and ion irradiated Fe(1.4 nm)/Cr(t_Cr) samples with t_Cr=0.97 nm (a,b), t_Cr=1.4 nm (c,d) and t_Cr=1.55 nm (e,f). The curves 1, 2 and 3 denote samples in the as-deposited state and irradiated with ion doses of 2×10¹³ and 8×10¹³ Ar/cm², respectively.

(17K)
Fig. 3. Ratio of bilinear (J₁) and biquadratic (J₂) components of interlayer exchange coupling vs. ion dose, shown for t_Cr indicated.

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Fig. 4. The saturation field H_S (a), GMR amplitude (b), antiferromagnetically coupled fraction F_AF (c) and GMR/F_AF (d) of Fe(1.4 nm)/Cr(t_Cr) multilayers as a function of t_Cr for as-deposited samples (!) and after successive irradiation with ion doses 5×10¹² Ar/cm² (,); 1×10¹³ Ar/cm² (7); 2×10¹³ Ar/cm² (B); 8×10¹³ Ar/cm² (Λ); 1.2×10¹⁴ Ar/cm² (Σ); 2×10¹⁴ Ar/cm² (+).

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