Speaker
Description
Magnetic skyrmions are topologically protected spin structures that can be manipulated by various external stimuli with minimal energy input, making them attractive for future spintronic applications [1]. Skyrmion hosting materials have been proposed as solutions for many current global issues, especially around energy consumption and usage, with the potential for skyrmion hosts to provide more energy-efficient memory devices with quicker storage and retrieval of information [2,3]. Cu2OSeO3 was the first insulating multiferroic material observed to host magnetic skyrmions under specific conditions [4]. It possesses a magnetic structure with both ferromagnetic and antiferromagnetic superexchange interactions and has a 3-up 1-down ferrimagnetic arrangement of Cu2+ ions [5]. The competition between Heisenberg exchange and Dzyaloshinskii–Moriya interactions induces a gradual canting of spins, which under specific conditions stabilises skyrmion textures: H =-∑ijJij Si ∙ Sj +∑ij Dij ∙ [(Si) × (Sj)] - h0m [4]. Previous research has focused on doping either the magnetic (Cu2+) or non-magnetic (Se4+) sites individually, observing changes to the skyrmion formation conditions through X-ray, neutron and magnetisation techniques [6–8]. Upon doping, the magnetisation and direction of the competing interactions are altered. The current project aims to investigate the effects of doping both metal sites simultaneously, allowing for a further understanding of the formation of skyrmions.
In this work, (Cu1-xZnx)2O(Se1-yTey)O3 [0 ≤ x ≤ 0.2] [0 ≤ y ≤ 0.2] was synthesised with the lattice expanding upon positive chemical pressure. The strong Cu2-Cu2 ferromagnetic interactions decrease in length while the weak and strong Cu1-Cu2 antiferromagnetic and the weak Cu2-Cu2 ferromagnetic interactions increase, resulting in the Cu-Cu interactions elongating overall. Magnetisation studies show a change in the magnetic transition temperatures upon doping, which varies to both the undoped and single-doped samples. Additionally, a drop in the magnetic saturation was observed, which differs from the single-doped samples, along with differences in the observed magnetic phases using small-angle neutron scattering under specific conditions.
| Field of Condensed Matter | Magnetism |
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