Electronic Properties of Air‐Sensitive Nanomaterials Probed with Microwave Impedance Measurements

Abstract

Characterization of electronic properties of novel materials is of great importance for exploratory materials development and also for the discovery of new correlated phases. As several novel compounds are available in powder form only, contactless methods, which also work on air‐sensitive samples, are highly desired. We present that the microwave cavity perturbation technique is a versatile tool to study conductivity in such systems. The examples include studies on semiconducting–metallic crossover in carbon nanotubes upon alkali doping, study of vortex motion in the K3C60 superconductor, and the characterization of various alkali atom doped phases of black phosphorus.

Tuning Conductivity and Spin Dynamics in Few‐Layer Graphene via In Situ Potassium Exposure

“…Microwave conductivity measurements were performed with the cavity perturbation technique [ 30,31 ] in a custom‐built high‐temperature setup. The method is proved to give meaningful information about the conductivity of porous and air‐sensitive samples [ 32 ] and well suited to study in situ changes. The used copper cavity has an unloaded quality factor of Q 0 = 10 000 and a resonance frequency, , whose temperature dependence is considered.…”

“…As the FLG material is known to have low conductivity compared with metals, the relation is used, [ 32,34 ] where ρ is the resistivity of the sample. As the microwave conductivity cannot yield absolute conductivity values, other important parameters, e.g., charge carrier mobility, remain inaccessible with this method.…”

Tuning Conductivity and Spin Dynamics in Few-Layer Graphene via In Situ Potassium Exposure

“…Microwave conductivity measurements were performed with the cavity perturbation technique 30,31 in a custombuilt high-temperature setup. The method is proven to give meaningful information about the conductivity of porous and air-sensitive samples 32 and well suited to study in situ changes. The used copper cavity has an unloaded quality factor of Q 0 = 10, 000 and a resonance frequency, f 0 ≈ 10.2 GHz, whose temperature dependence is taken into account.…”

“…Since the FLG material is known to have low conductivity compared to metals, the Q ∼ relation is used 32,34 , where is the resistivity of the sample.…”