RESUMO
Tuning magnetic properties in layered van der Waals (vdW) materials has captured significant attention due to the efficient control of ground states by heterostructuring and external stimuli. Electron doping by electrostatic gating, interfacial charge transfer, and intercalation is particularly effective in manipulating the exchange and spin-orbit properties, resulting in a control of Curie temperature (TC) and magnetic anisotropy. Here, an uncharted role of intercalation is discovered to generate magnetic frustration. As a model study, Na atoms are intercalated into the vdW gaps of pristine Cr2Ge2Te6 (CGT) where generated magnetic frustration leads to emerging spin-glass states coexisting with a ferromagnetic order. A series of dynamic magnetic susceptibility measurements/analysis confirms the formation of magnetic clusters representing slow dynamics with a distribution of relaxation times. The intercalation also modifies other macroscopic physical parameters including the significant enhancement of TC from 66 to 240 K and the switching of magnetic easy-hard axis direction. This study identifies intercalation as a unique route to generate emerging frustrated spin states in simple vdW crystals.
RESUMO
Layered van der Waals (vdW) magnets can maintain a magnetic order even down to the single-layer regime and hold promise for integrated spintronic devices. While the magnetic ground state of vdW magnets was extensively studied, key parameters of spin dynamics, like the Gilbert damping, crucial for designing ultra-fast spintronic devices, remains largely unexplored. Despite recent studies by optical excitation and detection, achieving spin wave control with microwaves is highly desirable, as modern integrated information technologies predominantly are operated with these. The intrinsically small numbers of spins, however, poses a major challenge to this. Here, we present a hybrid approach to detect spin dynamics mediated by photon-magnon coupling between high-Q superconducting resonators and ultra-thin flakes of Cr2Ge2Te6 (CGT) as thin as 11 nm. We test and benchmark our technique with 23 individual CGT flakes and extract an upper limit for the Gilbert damping parameter. These results are crucial in designing on-chip integrated circuits using vdW magnets and offer prospects for probing spin dynamics of monolayer vdW magnets.
