Einstein in an iron crystal

Discussion in 'General Science & Technology' started by paddoboy, Dec 29, 2016.

  1. paddoboy Valued Senior Member

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    Einstein in an iron crystal
    December 21, 2016

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    Angle-resolved photoemission spectra of an iron sample dependent on the direction of magnetization. Copyright: Forschungszentrum Jülich
    Tiny relativistic effects form the basis of the functionalities in modern technology, as exemplified in magnetic hard disks and data storage media. Now for the first time, scientists have directly observed features in an electronic structure that could not be seen previously.



    Read more at: http://phys.org/news/2016-12-einstein-iron-crystal.html#jCp
     
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  3. paddoboy Valued Senior Member

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    http://journals.aps.org/prx/abstract/10.1103/PhysRevX.6.041048


    Fermi Surface Manipulation by External Magnetic Field Demonstrated for a Prototypical Ferromagnet

    ABSTRACT
    We consider the details of the near-surface electronic band structure of a prototypical ferromagnet, Fe(001). Using high-resolution angle-resolved photoemission spectroscopy, we demonstrate openings of the spin-orbit-induced electronic band gaps near the Fermi level. The band gaps, and thus the Fermi surface, can be manipulated by changing the remanent magnetization direction. The effect is of the order of ΔE=100meVand Δk=0.1Å−1. We show that the observed dispersions are dominated by the bulk band structure. First-principles calculations and one-step photoemission calculations suggest that the effect is related to changes in the electronic ground state and not caused by the photoemission process itself. The symmetry of the effect indicates that the observed electronic bulk states are influenced by the presence of the surface, which might be understood as related to a Rashba-type effect. By pinpointing the regions in the electronic band structure where the switchable band gaps occur, we demonstrate the significance of spin-orbit interaction even for elements as light as 3d ferromagnets. These results set a new paradigm for the investigations of spin-orbit effects in the spintronic materials. The same methodology could be used in the bottom-up design of the devices based on the switching of spin-orbit gaps such as electric-field control of magnetic anisotropy or tunneling anisotropic magnetoresistance.

     
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