Electric-field control of anomalous and topological Hall effects in oxide bilayer thin films

Yuki Ohuchi,Masashi Kawasaki,Yoshinori Tokura,Masaki Uchida,Yusuke Kozuka,Naoki Ogawa,Jobu Matsuno

doi:10.1038/s41467-017-02629-3

Yuki Ohuchi, Masashi Kawasaki + Show 5 more

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https://doi.org/10.1038/s41467-017-02629-3

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Abstract

One of the key goals in spintronics is to tame the spin-orbit coupling (SOC) that links spin and motion of electrons, giving rise to intriguing magneto-transport properties in itinerant magnets. Prominent examples of such SOC-based phenomena are the anomalous and topological Hall effects. However, controlling them with electric fields has remained unachieved since an electric field tends to be screened in itinerant magnets. Here we demonstrate that both anomalous and topological Hall effects can be modulated by electric fields in oxide heterostructures consisting of ferromagnetic SrRuO3 and nonmagnetic SrIrO3. We observe a clear electric field effect only when SrIrO3 is inserted between SrRuO3 and a gate dielectric. Our results establish that strong SOC of nonmagnetic materials such as SrIrO3 is essential in electrical tuning of these Hall effects and possibly other SOC-related phenomena.

Highlights

One of the key goals in spintronics is to tame the spin-orbit coupling (SOC) that links spin and motion of electrons, giving rise to intriguing magneto-transport properties in itinerant magnets
In view of the fact that ultrathin films of itinerant magnets have been a playground for electrical manipulation of spin states[1, 15,16,17,18,19], an electric field applied to the ultrathin heterostructure may provoke effective manipulation of the spin state contending with screening effects by itinerant electrons of SrRuO3
In order to show this clearly, the variations of AHE (ΔρAHE) and topological Hall effect (THE) (ΔρTHE/ρTHE (0 V)) with different thickness of SrRuO3 films are shown in Fig. 4a, b, respectively, as a function of ρxx variation normalized by zerobias value (Δρxx/ρxx (0 V)) at various temperatures

Summary

Introduction

One of the key goals in spintronics is to tame the spin-orbit coupling (SOC) that links spin and motion of electrons, giving rise to intriguing magneto-transport properties in itinerant magnets Prominent examples of such SOC-based phenomena are the anomalous and topological Hall effects. In some itinerant ferromagnets such as SrRuO33, 4, the proportionality factor (RS) is governed by k-space monopoles, i.e., singularities originating from band-crossings gapped by SOC; not M but RS is potentially tuneable by electric field there Another intriguing example is the topological Hall effect (THE) originating from scalar spin chirality concomitant with non-coplanar spin structures such as in a frustrated pyrochlore magnet[5] and in metallic magnets characterized by a non-zero skyrmion number (Nsk)[6,7,8,9]. The electrical modulation is effective only when SrIrO3 is inserted between SrRuO3 and a gate dielectric, i.e., SrTiO3 This indicates the essential role of the strong SOC in nonmagnetic materials for the electrical tuning of these Hall effects and possibly other SOC-related phenomena

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