Electric field control of interfacial spins in ferroelectric/ferromagnetic junctions

Şen, Canhan (2018) Electric field control of interfacial spins in ferroelectric/ferromagnetic junctions. [Thesis]

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Electric field control of magnetization allows further miniaturization of integrated circuits for binary bit processing and data storage as it eliminates the need for bulky sophisticated systems to induce magnetic fields. Magnetoelectric coupling inherent to the bulk of multiferroic films or control of spin orientation in magnetic layers via piezoelectric strain in dual component composites have been two approaches standing out. Another magnetoelectric effect is spin-dependent screening that occurs at dielectric/ferromagnet interfaces which is of great importance for spin selective tunnel junctions. Here, we analyze the spin-dependent screening of ferroelectric polarization in a film interfacing ferromagnetic electrodes using the continuity equations in continuum media. The competition between the electrostatic and the magnetochemical potential in the FM electrodes gives rise to a reduction in the net magnetic moment near the interface due to spin mixing, extending to a distance comparable to the Thomas-Fermi screening length. Our continuum media treatment shows that the local spin population in spin subbands near the interfaces can dramatically deviate from bulk, which is in qualitative agreement with recent first principles results. We compute the tunneling currents for majority and minority spins using the Wentzel-Kramers-Brillouin approximation as a function of ferroelectric polarization. We find that the spin polarization tends to disappear for increasing values of ferroelectric polarization in direct connection with the increase in subband spin population for minority spins at the interface
Item Type: Thesis
Uncontrolled Keywords: Ferroelectrics. -- Ferromagnets. -- Tunnelling magnetoresistance (TMR). -- Spin-dependent screening. -- Electrostatics. -- Electroceramics. -- Intelligent materials. -- Magnetic materials. -- Tunelling. -- Elektroseramik. -- Akıllı malzemeler. -- Manyetik malzemeler. -- Ferroelektrikler. -- Ferromagnetler. -- Tunelleme magnetodirenç (TMD). -- Spin-bağımlı perdeleme. -- Elektrostatik. -- Tünelleme
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
Divisions: Faculty of Engineering and Natural Sciences > Academic programs > Materials Science & Eng.
Faculty of Engineering and Natural Sciences
Depositing User: IC-Cataloging
Date Deposited: 11 Oct 2018 14:12
Last Modified: 26 Apr 2022 10:26
URI: https://research.sabanciuniv.edu/id/eprint/36624

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