How did Albert Fert discover GMR?
We were studying iron-chromium superlattices grown by molecular beam epitaxy, a technique that allows atomic-level precision. I remember the moment clearly: we measured the resistance as a function of magnetic field and saw a drop of nearly 50%. That curve—it told the whole story. We were surprised to find that the effect was far larger than any known magnetoresistance. My approach was systematic: first, we verified the sample quality with X-ray diffraction, then we varied the chromium layer thickness to isolate the cause. The theoretical explanation came later, building on the concept of spin-dependent scattering. This discovery was not accidental—it came from years of preparing high-quality samples and designing experiments to probe their properties. The key is to prepare the sample with extreme care; without that, you might miss the effect entirely. This work directly launched the field of spintronics.
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