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The discovery of the Hall effect in an antiferromagnet breaks with conventional scientific wisdom. It was made in a crystal comprising antiferromagnetically orderd atoms which, on their own, would generate no Hall current, in agreement with Néel. The crystal also includes non-magnetic atoms which, on their own, would also only allow for the ordinary Ohm’s current. However, with a suitable combination of both the antiferromagnetic and non-magnetic atoms present in the crystal, the Hall effect arises. It is a striking example of the ancient “the whole is greater than the sum of its parts”.
Description
Figure Top row: Left - Hall current in an external magnetic field applied to crystal comprising non-magnetic atoms. Middle – Hall current in a ferromagnet, the blue symbol marks unwanted ferromagnetic stray field. Right – Hall current in a crystal comprising antiferromagnetic and non-magnetic atoms. Middle row: Left - Ordinary Ohm’s current in a crystal comprising only non-magnetic atoms. Right – Same as left in a crystal comprising only antiferromagnetic atoms. Bottom row is a replica of the top row with highlighted unique control of Hall signs: Left – oppositely charged current carriers. Middle - opposite magnetization. Right - opposite positions of non-magnetic atoms.
Contact person: prof. Tomáš Jungwirth, Ph.D.