Anisotropy of exchange stiffness based on atomic-scale magnetic properties in the rare-earth permanent magnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Nd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Fe</mml:mi><mml:mn>14</mml:mn></mml:msub><mml:mi mathvariant="normal">B</mml:mi></mml:mrow></mml:math>
Physical review. B./Physical review. B