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Will-Cole, A.R.; Hart, James L.; Lauter, Valeria; Grutter, Alexander; Dubs, Carsten; Lindner, Morris; Reimann, Timmy; Pearce, Charles J.; Monson, Todd M.; Cha, Judy J.; Heiman, Don; Sun, Nian X.

Yttrium iron garnet (Y₃Fe₅O₁₂; YIG) has a unique combination of low magnetic damping, high spin-wave conductivity, and insulating properties that make it a highly attractive material for a variety of applications in the fields of magnetics and spintronics. While the room-temperature magnetization dynamics of YIG have been extensively studied, there are limited reports correlating the low-temperature magnetization dynamics to the material structure or growth method. Here, in this study, we investigate liquid phase epitaxy grown YIG films and their magnetization dynamics at temperatures down to 10 K. We show there is a negligible increase in the ferromagnetic resonance linewidth down to 10 K, which is unique when compared with YIG films grown by other deposition methods. From the broadband ferromagnetic resonance measurements, polarized neutron reflectivity, and scanning transmission electron microscopy, we conclude that these liquid phase epitaxy grown films have negligible rare-earth impurities present, specifically the suppression of Gd diffusion from the Gd₃Ga₅O₁₂ (GGG) substrate into the Y₃Fe₅O₁₂ film, and therefore negligible magnetic losses attributed to the slow-relaxation mechanism. Overall, liquid phase epitaxy YIG films have a YIG/GGG interface that is five times sharper and have ten times lower ferromagnetic resonance linewidths below 50 K than comparable YIG films by other deposition methods. Thus, liquid phase epitaxy grown YIG films are ideal for low-temperature experiments/applications that require low magnetic losses, such as quantum transduction and manipulation via magnon coupling.

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TYPE Journal Article YEAR 2023

DOI OSTI DOI OSTI

Influence of surface adsorption on MoS2 memtransistor switching kinetics

Applied Physics Letters

Cain, John M.; Chou, Stanley S.; Lu, Tzu-Ming L.; Yan, Xiaodong; Liu, Stephanie E.; Qian, Justin H.; Zeng, Thomas T.; Sangwan, Vinod K.; Hersam, Mark C.

Sulfur-deficient polycrystalline two-dimensional (2D) molybdenum disulfide (MoS2) memtransistors exhibit gate-tunable memristive switching to implement emerging memory operations and neuromorphic computing paradigms. Grain boundaries and sulfur vacancies are critical for memristive switching; however, the underlying physical mechanisms are not fully understood. Furthermore, the adsorption of water and gaseous species strongly perturbs electronic transport in monolayer MoS2, and little work has been done to explore the influence of surface interactions on defect-related kinetics that produces memristive switching. Here, we study the switching kinetics of back-gated MoS2 memtransistors using current transient measurements in a controlled atmosphere chamber. We observe that adsorbed water molecules lead to suppression of the electronic trap-filling processes concomitant with the resistive switching process, resulting in altered kinetics of the resistive switching. Additionally, using the transient response from “bunched” drain voltage pulse trains performed as a function of temperature, we extract the energy of the affected trap state and find that it places the trap roughly midgap [ E T = E C - 0.7 ( ± 0.4 ) eV]. Our results highlight the importance of controlling for surface interactions that may affect switching kinetics in 2D memtransistors, synaptic transistors, and related memory devices.

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TYPE Journal Article YEAR 2023

DOI OSTI Scopus

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