Tailored magnetic profiles in ultrahigh conductivity PdCoO2 using helium implantation

The delafossite PdCoO2 consists of alternating layers of highly conductive palladium and electronically localized octahedral cobalt. While PdCoO2 is diamagnetic in bulk crystals, both Co and Pd layers exhibit magnetic metastability. We have recently demonstrated [1] that small perturbations associated with helium implantation can induce and continuous tune ferromagnetism. This positions PdCoO2 as a unique and promising material for future spintronics, serving as a platform for designing magnetism through nanoscale helium patterning [2]. A key question remains regarding the fundamental mechanisms that give rise to magnetization as well as routes to achieve controllable and targeted magnetic properties. In this talk, we address this question by contrasting magnetic and implantation depth profiles from low-energy muon spectroscopy measurements alongside simulated implantation profiles. Our analysis reveals that the implanted helium atoms alone does not account for magnetism near the surface regions, suggesting defect complexes can also give rise to magnetic sites. Understanding all the routes to controllable create magnetism in PdCoO2 will enables tailoring implantation conditions to achieve desired functional properties for future applications requiring strong-spin orbit coupling as well as high conductivity, low energy-loss materials.

[1] Brahlek, M. et al. Emergent Magnetism with Continuous Control in the Ultrahigh-Conductivity Layered Oxide PdCoO2. Nano Letters 23, 7279–7287 (2023).

[2] Toulouse, C. et al. Patterning enhanced tetragonality in BiFeO3 thin films with effective negative pressure by helium implantation. Physical Review Materials 5, 024404 (2021).