Resistance Paints the Secret Angles of a Magnetic Dance ⚡ экспресс
Using the spin Hall effect method (SMR), the influence of the direction of an external magnetic field on the resistance of a platinum-multiferroic (BiFeO3) system was studied. Typically, for ferromagnets the signal phase shift is 0°, for antiferromagnets — 90°. In this work, it was discovered that in epitaxial BiFeO3 films this shift can take on a wide variety of values, varying from sample to sample. This deviation from the pattern is like a magnetic 'fingerprint' unique to each sample, even though the composition is the same. This points to complex magnetic interactions at the interface and calls for new explanations.
Using a method similar to spectroscopy (magnetic sensing), scientists pass a current through a multilayer film and observe the orientation of the microscopic magnetic arrows inside. Previously, everything was predictable: in some materials, the arrows aligned only along the current, in others—strictly across it. But in bismuth ferrite with a platinum coating, a glitch occurred. As the external magnet rotated, the resistance changed as if each arrow forgot the common alignment and chose its own angle—10°, 37°, 72°.
By measuring the magnitude of this chaotic signal, researchers hope to understand the cause of the entropic disorder. The solution promises the memory of the future: data will be stored not in bytes, but in twisted vortices of the magnetic field. By the way, bismuth ferrite is a two-in-one: it's both a magnet and an electric accumulator, changing properties at the slightest flip.
🎯 Bismuth ferrite is a multiferroic: it combines ferromagnetism and ferroelectricity, working as two materials in one.