Emergence of Topological Hall Effect in a SrRuO₃ Single Layer

Abstract

Topological Hall effect (THE), appearing as bumps and/or dips in the Hall resistance curves, is considered as a hallmark of the skyrmion spin texture originated from the inversion symmetry breaking and spin–orbit interaction. Recently, Néel‐type skyrmion is proposed based on the observed THE in 5d transition metal oxides heterostructures such as SrRuO3/SrIrO3 bilayers, where the interfacial Dzyaloshinskii–Moriya interaction (DMI), due to the strong spin–orbit coupling (SOC) in SrIrO3 and the broken inversion symmetry at the interface, is believed to play a significant role. Here the emergence of THE in SrRuO3 single layers with thickness ranging from 3 to 6 nm is experimentally demonstrated. It is found that the oxygen octahedron rotation in SrRuO3 also has a significant effect on the observed THE. Furthermore, the THE may be continuously tuned by an applied electrical field. It is proposed that the large SOC of Ru ions together with the broken inversion symmetry, mainly from the interface, produce the DMI that is responsible for the observed THE. The emergence of the gate‐tunable DMI in SrRuO3 single layer may stimulate further investigations of new spin–orbit physics in strong SOC oxides.

Unconventional anomalous Hall effect driven by oxygen-octahedra-tailoring of the SrRuO3 structure

“…Tetragonal structure was reported also for epitaxial SRO films grown on orthorhombic GdScO 3 (110) and NdGaO 3 (110) substrates [19,26], on GdScO 3 -buffered SrTiO 3 (100) [27] and for oxygen-deficient epitaxial SRO films grown on SrTiO 3 (100) [28].…”

Overcoming the Limits of the Interfacial Dzyaloshinskii–Moriya Interaction by Antiferromagnetic Order in Multiferroic Heterostructures

“…[ 38,48 ] In the authors' previous work, they had effectively modulated oxygen octahedral rotation via oxygen engineering, which gave rise to THE in SRO layer with a thickness of 3–6 nm. [ 15 ] Based on these reasons, they introduced a weak bulk DMI constant D = 3.8 × 10 −4 J m −2 for SRO in their simulations.…”

“…[ 12 ] Moreover, oxygen octahedral rotation/tilting [ 13 ] and microstructural defects [ 14 ] are demonstrated as additional origins of the DMI. Our previous work [ 15 ] found the emergence of THE in SRO single layer with a thickness of 7–15 unit cells through the modulation of RuO 6 oxygen octahedra via oxygen engineering. Considering that microstructural defects in the sample are uncontrollable, we propose a new approach to stabilize magnetic topological states by antiferromagnetic order.…”

Noncollinear spintronics and electric-field control: a review

“…The authors attributed the modulation to the variation of the spin-orbit coupling at the interface of SrRuO3 and SrIrO3 and emphasized the importance of nonmagnetic interlayer SrIrO3 that has large spin-orbit coupling in this work. and c +200 V. [48] Most recently, Qin et al [49] realized the electric-field control of topological Hall effect in a single SrRuO3 layer and they applied electric fields by ionic liquid (Fig. 15a).…”

“…In this work, the electric potential gradient in the surface of SrRuO3 tunes the spin-orbit coupling thus arouse the change of Dzyaloshinskii-Moriya interaction rather than magnetic exchange energy or the anisotropy energy of the single SrRuO3 layer. [ 49] On the other side, in multiferroic MnWO4, Finger et al [50] demonstrated that the switch of the chiral component by applied electric fields. As given in Fig.16a-d, after cycling the voltage, the chiral radio can always return to the initial value.…”