This “semimetal” crystal consists of repeating unit cells such as the one to the left, which has a square top and rectangular sides. The spheres represent silicon (violet), aluminum (turquoise), and — in gold — neodymium (Nd) atoms, the last of which are magnetic. Understanding the special magnetic properties of the material requires nine of these unit cells, shown as the larger block to the right (which has a unit single cell outlined in red). This 3x3 block shows green “Weyl” electrons traveling diagonally across the top of the cells and affecting the magnetic spin orientation of the Nd atoms. A special property of the Weyl electron is the locking of its spin direction, which either points parallel or antiparallel to the direction of its motion, as represented by the small arrows in the Weyl electrons. As these electrons travel along the four gold Nd atoms, the Nd spins reorient themselves into a “spin spiral” which can be imagined as pointing successively in the 12 o’clock direction (closest to viewer with red arrow pointing upward), 4 o’clock (blue arrow), 8 o’clock (also in blue) and again 12 o’clock (farthest from viewer and again in red). Lines of Nd atoms stretch through many layers of the crystal, offering many instances of this unusual magnetic pattern.
Credit: N. Hanacek/NIST
An exotic form of magnetism has been discovered and linked to an equally exotic type of electrons, according to scientists who analyzed a new crystal in which they appear at the National Institute of Standards and Technology (NIST). The magnetism is created and protected by the crystal’s unique electronic structure, offering a mechanism that might be exploited for fast, robust information storage devices.
The newly invented material has an unusual structure that conducts electricity but makes the flowing electrons beha ..
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