Abstract
Electric-field-induced magnetic switching can lead to a new paradigm of ultra-low power nonvolatile magnetoelectric random access memory (MeRAM). To date the realization of MeRAM relies primarily on ferromagnetic (FM) based heterostructures which exhibit low voltage-controlled magnetic anisotropy (VCMA) efficiency. On the other hand, manipulation of magnetism in antiferromagnetic (AFM) based nanojunctions by purely electric field means (rather than E-field induced strain) remains unexplored thus far. Ab initio electronic structure calculations reveal that the VCMA of ultrathin FeRh/MgO bilayers exhibits distinct linear or nonlinear behavior across the AFM to FM metamagnetic transition depending on the Fe- or Rh-interface termination. We predict that the AFM Fe-terminated phase undergoes an E-field magnetization switching with large VCMA efficiency and a spin reorientation across the metamagnetic transition. In sharp contrast, while the Rh-terminated interface exhibits large out-of-plane (in-plane) MA in the FM (AFM) phase, its magnetization is more rigid to external E-field. These findings demonstrate that manipulation of the AFM Néel-order magnetization direction via purely E-field means can pave the way toward ultra-low energy AFM-based MeRAM devices.
Highlights
Spintronics offers a promising solution[1, 2] to the major challenging issues related to the scaling of Si-based complementary metal-oxide-semiconductor (CMOS) technology because of the advantages of combing the spin and charge degrees of freedom and its ability to manipulate magnetic states in low-power-consumption ways[3, 4]
To date the realization of magnetoelectric random access memory (MeRAM) relies primarily on ferromagnetic (FM) based heterostructures consisting of heavy metal (HM/)FM/insulator(HM = Ta, Hf, Mo) nanojunctions[13, 14, 16,17,18]
We have predicted that epitaxial strain in HM/FM/ insulator heterostructures gives rise to giant voltage-controlled magnetic anisotropy (VCMA) efficiency[22, 23]
Summary
For the Fe-terminated surface we find that the G-AFM is the most stable phase for both the free standing 5-ML FeRh and FeRh/MgO thin films regardless of the strain on FeRh (−0.5% < ηFeRh < 0.5%) with ∆E = EFM − EG−AFM of 23 meV/Fe and 20 meV/Fe, respectively. Where Ψ↓o(Eo↓) and Ψ↓u(Eu↓) are the one-electron occupied and unoccupied minority-spin states (energies) of band index n and wave vector k (omitted for simplicity), ξ is the SOC constant, and Lx(z) is the x(z) component of the orbital angular momentum operator This expression allows to understand the underlying origin of the effect of strain or E-field on the MA. In the low-bias regime the cViCenMt,Aε =is 1p0roips othrteiodniealletcotrtihcecEon-fsitealdntinofththeeinMsugOlationr,tVhCe MraAng=e oβf EstMragOin=(~β±E0ex.5t/7ε%, w)2h2,e2r3e, β is and the Eext
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
