Observation of Néel Skyrmions in an Exchange Coupled Cobalt/Palladium Based Multi-layers of Metallic Compounds at High Temperatures

Abstract

ABSTRACT In the class of cubic B20 transition metal silicides and germanides, the skyrmions and skyrmion lattices have so far been studied most extensively. Certain groups of materials in which skyrmions were identified include the Perovskites and Heusler systems. In this paper, the skyrmions chiral Neel characterization is illustrated via Lorentz transmission electron microscopy. Further utilizing magnetic-imaging and Hall-transport in a functionally viable multilayer sample, the topological-hall resistivity rises over a wide range of temperature and magnetic field with the isolated-skyrmion density is observed, verifying the effect of the skyrmion geometric-phase on electron transport. The observed bulk Neel skyrmions in an exchange coupled cobalt/palladium(Co/Pd) based multi-layers of metallic compounds at high temperatures up to a maximum of 220 K followed by a larger region characterized by spin from in-to out-of-plane. In fact, the skyrmions are extremely resilient to in-plane magnetic fields and can be stable in a zero magnetic field using appropriate cooling methods in field over a very wide ambient temperature of up to 5.5 K. At low temperatures (of < 13 K) the Neel skyrmions have been observed recently in distinct non-metallic compounds, in bulk crystals with broken inversion symmetry with a non-adiabatic footprint, multiband transport, interfacial interactions.