JPH028470B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a magnetoresistive material applicable to thin film magnetic sensors, thin film magnetic heads, etc. that utilize the ferromagnetic magnetoresistive effect. Conventional configurations and their problems Conventionally, materials that utilize the magnetoresistive effect of ferromagnetic thin films include permalloy (Ni-Fe alloy) and Ni-
Co alloys are known, and except for these alloys and surrounding alloys containing a third element, the materials used at room temperature have a Δρ/ρ value of 1.
~2% or more or specific resistance change Δρ,
No magnetoresistive material with a value greater than 0.3 μΩ·cm was known. In addition, both Ni-Fe and Ni-Co alloys have poor corrosion resistance and are easily corroded.Especially when they are made into thin films and used as thin film heads or magnetic sensors, the magnetic properties due to material corrosion It has been difficult to completely prevent the deterioration of On the other hand, when using conventional magnetoresistive materials, even the most widely used permalloy (Ni-Fe alloy)
The increase in resistivity change Δρ due to magnetoresistance in a saturated magnetized state is usually 0.6 μΩ·cm or less, and materials with even larger resistivity changes have been desired for magnetoresistive thin-film magnetic heads and the like. OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetoresistive material that has excellent corrosion resistance and a large change in specific resistance, and can be effectively used for perpendicular magnetic recording, longitudinal magnetic recording, and the like. Structure of the Invention The magnetoresistive material of the present invention is an alloy containing Co and Pd, and is characterized in that the composition range of Co is 35 to 60 atomic % and the composition range of Pd is 65 to 40 atomic %. That is. The magnetoresistive materials of the present invention include binary alloys of Co and Pd (Co-Pd alloys) and alloys in which other third elements are added thereto. The Co--Pd alloy is a solid solution alloy with a face-centered cubic lattice structure at room temperature, and exhibits ferromagnetism when Co contains 20 atomic % or more. Therefore, a ferromagnetic magnetoresistance effect becomes possible when the Co content is 20 atomic % or more, but alloys containing Co and Pd exhibit magnetoresistance different from that of Co itself. Its magnetic properties show relatively soft magnetism when Co is about 35 atomic % or more, and the coercive force is 20 Oe even in the sputter deposition method where the coercive force Hc becomes relatively large when Co is about 50 atomic % or more, as shown in Figure 1. Go down. Moreover, the magnetization value also increases monotonically as Co increases. Description of Examples Examples 1 to 6: Co having the composition shown in Table 1
A -Pd binary alloy was prepared and the specific resistance change Δρ and coercive force in response to a 60Hz alternating magnetic field were measured. The results are also shown in Table 1.

[Table] Figure 2 shows 60% of the Co-Pd alloy of Example 4.
The magnetoresistance change characteristics in response to an alternating current magnetic field of Hz are shown. In addition, Co-Pd shown in Examples 1 to 6 is shown in Fig. 3.
The relationship between resistivity change and Co composition of binary alloys is shown.
Co composition is 35 to 60 at% and Pd composition is 65 to 40
It can be seen from FIG. 3 that the specific resistance change has a peak in the atomic percent range. Examples 7 to 10: Co and Pd were further added with Ni or Fe as a third element to produce alloys having the compositions shown in Table 2, and changes in resistivity and coercive force were measured in the same manner as Examples 1 to 6. It was measured. The results are also shown in Table 2.

[Table] Adding tertiary elements (Ni, Fe, Cu, etc.) for various purposes with Co and Pd atomic ratios in the range of approximately 1.5 to 0.43, with Co and Pd atomic ratios corresponding to peak composition regions. Even in such a multi-component alloy, sufficiently large magnetoresistance properties can be expected. In Examples 7 to 10, the Co composition as described above was also almost the same.
A high change in resistivity was confirmed within the range of 35 to 60 atomic % and 65 to 40 atomic % of Pd composition. Example 11 (corrosion resistance test): Each of the samples obtained in Examples 1 to 10
A high-temperature, high-humidity test was conducted in which the Co-Pd alloy was kept at 60°C and 95% humidity for 10 days. As a result, in the conventional vermalloy thin film, bits were generated throughout the film surface, but no change was observed in the Co-Pd alloy thin film. Effects of the Invention According to the present invention, it is possible to obtain a ferromagnetic magnetoresistive material that has excellent corrosion resistance and a high change in specific resistance.

[Brief explanation of drawings]

Figure 1 is a graph showing changes in coercive force at room temperature with respect to Co composition in Co-Pd alloys, Figure 2 is a graph showing magnetoresistance characteristics of the Co-Pd alloy obtained in Example 4, and Figure 3 is Co in Co-Pd binary alloy
It is a graph showing the relationship between composition and specific resistance change Δρ.

Claims (1)

[Claims] 1. An alloy containing Co and Pd, wherein the composition range of Co is 35 to 60 atomic % and the composition range of Pd is 65 atomic %.
A magnetoresistive material characterized by ~40 atomic %. 2. The magnetoresistive material according to claim 1, wherein the alloy is a binary alloy of Co and Pd.