High figure of merit magneto-optics from interfacial skyrmions on topological insulators

Abstract

In the Kerr rotation geometry, magneto optic memory devices typically suffer from low figure-of-merit (FOM) and long write times. We show that skyrmions formed at the interface of a thin-film multiferroic and a topological insulator can give rise to high FOM magneto optic Kerr effects (MOKEs). Huge differential MOKE can arise in parts of the phase diagram. Resonance like features in the MOKE spectra arising from the induced low energy TI bandgap, the multiferroic-film thickness, and the high energy Drude like behavior are resolved and explained. The Fermi level dependence of the MOKE signatures is distinct for the different magnetic textures. This has broad implications for magnetic texture characterization, electro-optic modulators and isolators and high density magnetic optic memory. PACS numbers: Magneto-optic (MO) phenomenon such as Kerr and Faraday rotations, Voigt effect, magneto-plasma reflections and cyclotron resonances arise from broken time reversal symmetry. Some MO effects also arise from the electronic structure's topology, and hence are used to study quantum hall effects[1], Kerr rotations in topological insulators (TIs)[2, 3], magnetoelectric optical effects[4, 5], magneto-chiral effects[6], and skyrmions and their Hall effects[7-9].arXiv:1805.02799v1 [cond-mat.mes-hall]

Magneto-Optical and Muliferroic Properties of Transition-Metal (Fe, Co, or Ni)-Doped ZnO Layers Deposited by ALD

“…We suppose that the observed extreme variations in the MO Kerr response are related to the complex synergetic influence of all noted factors. Various types of materials demonstrate such enhanced MOKE polarization rotation, some of which share the similar universal mutliferroic nature to that for the investigated TMO/ZnO layersnanostructured plasmonic dielectrics, artificially nano-engineered metamaterials, 2D TM dichalcogenides, and topological insulators …”

“…Various types of materials demonstrate such enhanced MOKE polarization rotation, some of which share the similar universal mutliferroic nature to that for the investigated TMO/ZnO layers—nanostructured plasmonic dielectrics, 46 artificially nano-engineered metamaterials, 47 2D TM dichalcogenides, and topological insulators. 48 …”

Strong Magneto-Optical Kerr Effects in Ni-Doped ZnO Nanolaminate Structures Obtained by Atomic Layer Deposition

“…The prospects of the possible magnetism implication with soft magnetic behavior under an applied magnetic field in undoped ZnO is usually analyzed within the framework of the defect-induced d0 mechanism [45]. Тhe net spin polarization is mediated by interrelated structural and stoichiometric deviations such as anion (oxygen VO) or cation (Zink VZn) vacancies as well as surface and interface/substrate effects [31][32][33]. The complexity of magnetic effects expands even more when room temperature ferromagnetism [2,46] is achieved via TM magnetic doping effects, as in the case of ZnO:Ni with further alteration of the chemical phase composition and possible foreign magnetic clusters embedded in the main ZnO matrix.…”

“…The prospects of the possible magnetism implication with soft magnetic behavior under an applied magnetic field in undoped ZnO is usually analyzed within the framework of the defect-induced d 0 mechanism [45]. The net spin polarization is mediated by interrelated structural and stoichiometric deviations such as anion (oxygen VO) or cation (Zink VZn) vacancies as well as surface and interface/substrate effects [31][32][33].…”

“…Some of the state-of-the-art developments are related to the novel antiferromagnetic spintronics, magneto-plasmonics, and 2D and topological materials and are especially focused on the improvement of spatial, temporal, and spectral resolution [28][29][30][31][32]. In addition, the recent advancements in the field of topological insulators can give new impulse for a revival of MOKE-based memory drive technology [33].…”