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Condensed Matter Physics

Unveiling multiferroic proximity effect in graphene

Profile image of Daniel LermaDaniel Lerma

2019, 2D Materials

https://doi.org/10.1088/2053-1583/AB5319
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20 pages

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Abstract

We demonstrate that electronic and magnetic properties of graphene can be tuned via proximity of multiferroic substrate. Our first-principles calculations performed both with and without spin-orbit coupling clearly show that by contacting graphene with bismuth ferrite BiFeO 3 (BFO) film, the spin-dependent electronic structure of graphene is strongly impacted both by the magnetic order and by electric polarization in the underlying BFO. Based on extracted Hamiltonian parameters obtained from the graphene band structure, we propose a concept of six-resistance device based on exploring multiferroic proximity effect giving rise to significant proximity electro-(PER), magneto-(PMR), and multiferroic (PMER) resistance effects. This finding paves a way towards multiferroic control of magnetic properties in two dimensional materials.

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Paolo Michetti

Physical Review B, 2011

Graphene-based materials show promise for spintronic applications due to their potentially large spin coherence length. On the other hand, because of their small intrinsic spin-orbit interaction, an external magnetic source is desirable in order to perform spin manipulation. Because of the flat nature of graphene, the proximity interaction with a ferromagnetic insulator (FI) surface seems a natural way to introduce magnetic properties into graphene. Exploiting the peculiar electronic properties of bilayer graphene coupled with FIs, we show that it is possible to devise very efficient gate-tunable spin-rotators and spin-filters in a parameter regime of experimental feasibility. We also analyze the composition of the two spintronic building blocks in a spin-field-effect transistor. 72.80.Vp, 85.75.Mm, Graphene with its high mobility 1 and potentially long spin lifetimes, is an attractive material for spintronics. In particular, spin relaxation lengths on the order of micrometers have been observed 2 , together with spin relaxation times of hundreds of picoseconds, which are still believed to be limited by extrinsic impurities 3,4 . More recent experiments reported the measurement of a spin lifetime up to 1 ns in graphene and even of several nanoseconds in bilayer graphene (BG) 5,6 . Moreover, tunnel-injection of spin into graphene has been recently achieved using Co ferromagnets, with the observation of the largest non-local magnetoresistance of any material 7 . Graphene quantum dots have been also identified as an ideal host for spin qubits 8 .

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  • Physics
  • Condensed Matter Physics
  • Materials Science

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