Magneticcorrelations in (FexCo1-x)NGeTe2Â vander Waals Crystals
In recent years, two-dimensional (2D) materials have been at the forefront of condensed matter research. The discovery of long-range magnetic order in 2D materials* has catapulted the search for new van der Waals (vdWs) materials with stable magnetic ordering above room temperature. An emergent class of such magnets is the compounds (Fe1-xDx)NGeTe2(N = 3, 4, and 5 and D = Ni or Co). In this talk, I will discuss the state of magnetic ordering over a wide field–temperature phase space in single crystals of the high-Tc ferromagnet (Fe1-xDx)NGeTe2 studied using magnetization, ferromagnetic resonance (FMR), and electrical transport measurements. For the x = 0 compounds, our findings demonstrate an amagnetic phase transition from a collinear to a complex non-collinear magnetic order near the temperature T* ≈ 160 K, below which the magnetic susceptibility is reduced, the FMR linewidth broadened, and the anomalous Hall resistivity suppressed. I will also discuss how the insertion of Co and Ni at the Fe sites affects these results and leads to new magnetic phases.
* 1)Jae – Ung Lee et al (Nano Lett. 16, 7433 (2016))
 2) C. Gong et al (Nature 546, 265 (1017)
3) Bevin Huang et al (Nature 546, 270 (2017)
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This research has been conducted jointly with postdoctoral associate Rabindra Basnet and funded by the DOD Center of Excellence on 2D materials research under grant No. W911NF2120213.