How to calculate saturation magnetisation in GMR effect?

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In summary, the conversation is about a student working on their laboratory report on GMR effect and needing to calculate the antiferromagnetic coupling for their multilayers. They have resistance versus magnetic field graphs and want to use the equation ##J_{AF}=-\frac{\mu_0 M_S t}{4}H_S##, but need to find the unknown anisotropy constant, K. They have found some data for permalloy and will use it in their calculations.
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majas
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Homework Statement


Hello everyone. This is my first post.
I'm working now on my laboratory report from GMR effect. I have to calculate the antiferromagnetic coupling for my multilayers. I have only resistance versus magnetic field graphs.

Homework Equations


I want to use the equation:
##J_{AF}=-\frac{\mu_0 M_S t}{4}H_S##
It's easy to find ##H_S##, ##\mu_0## and t is given, and I need ##M_S##.

The Attempt at a Solution


I have found equation $$H_S=\frac{K}{M_S},$$ but there is next unknown K, which is the anisotropy constant, and I'm not sure how it is for permalloy which the multilayers were made.

Thank you for your help.
 
Physics news on Phys.org

1. How is saturation magnetisation defined in GMR effect?

Saturation magnetisation in GMR (giant magnetoresistance) effect refers to the maximum magnetic moment that can be achieved in a material. It is the point at which the material's magnetic domains are all aligned and further increase in the applied magnetic field does not result in any increase in magnetisation.

2. What is the formula for calculating saturation magnetisation in GMR effect?

The formula for calculating saturation magnetisation in GMR effect is MS = Nμ0M, where MS is the saturation magnetisation, N is the number of magnetic moments per unit volume, and μ0 and M are the permeability of free space and the material's magnetisation, respectively.

3. How does the composition of a material affect its saturation magnetisation in GMR effect?

The composition of a material, specifically the type and arrangement of magnetic atoms, can greatly affect its saturation magnetisation in GMR effect. For example, materials with higher concentrations of magnetic atoms or those with a more ordered atomic structure tend to have higher saturation magnetisation values.

4. Can saturation magnetisation be measured experimentally in GMR effect?

Yes, saturation magnetisation can be measured experimentally in GMR effect using techniques such as vibrating sample magnetometry or SQUID (superconducting quantum interference device) magnetometry. These methods involve applying an external magnetic field to the material and measuring its resulting magnetisation.

5. How does temperature affect saturation magnetisation in GMR effect?

Temperature can affect saturation magnetisation in GMR effect by altering the thermal energy of the material's magnetic atoms. As temperature increases, the thermal energy also increases, making it more difficult for the material's magnetic moments to align and resulting in a decrease in saturation magnetisation.

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