Adaptive microwave impedance memory effect in a ferromagnetic insulator

Abstract

Adaptive electronics, which are often referred to as memristive systems as they often rely on a memristor (memory resistor), are an emerging technology inspired by adaptive biological systems. Dissipative systems may provide a proper platform to implement an adaptive system due to its inherent adaptive property that parameters describing the system are optimized to maximize the entropy production for a given environment. Here, we report that a non-volatile and reversible adaptive microwave impedance memory device can be realized through the adaptive property of the dissipative structure of the driven ferromagnetic system. Like the memristive device, the microwave impedance of the device is modulated as a function of excitation microwave passing through the device. This kind of new device may not only helpful to implement adaptive information processing technologies, but also may be useful to investigate and understand the underlying mechanism of spontaneous formation of complex and ordered structures.

Hybrid Resonance Memory Metamaterial with Full‐Wave Operation

“…To illustrate the idea of the present study, we consider a microstrip resonator coupled with two thin MDs ( Figure a,b). To simplify the model, we assume that the domain wall can move and stay stably, and that the demagnetization field is dominant to the effective internal magnetic field of two MDs so that the N‐FMR frequency is determined by the domain wall position (Section S1, Supporting Information) . In response to microwave magnetic field ( H rf ) of the microstrip resonator, where the H rf is perpendicular to the magnetization direction of MDs, the magnetic moments of two MDs precess around their magnetization directions.…”

“…Particularly, because the MD structure depends on the magnetic history, the variations of the N‐FMR frequency and the hybrid resonance show a memristive behavior for the input microwave signal. Then, one can express the memristive response of the present system aswhere a and b are the input and the output microwaves, S and Z h are the scattering parameter and the microwave memory impedance (mempedance) of the resonator, ω m and a m are the frequency and amplitude of the input microwave resulting in a change of the MD structure. We note that the change of MD structure only occurs when the precession amplitude of the MDs exceeds some critical value, and the coupled resonator maintains its memory state for an input microwave signal which does not result in a change the MD structure.…”

“…Here, we report the memory metamaterial based on the hybrid resonance of the metamaterial‐ferromagnetic system. Previously, we showed that the natural (or zero field) ferromagnetic resonance (N‐FMR) of a ferromagnetic insulator can be tuned reversibly and nonvolatilely by the input microwave signal . Because the hybrid resonance depends on the ferromagnetic resonance (FMR) of the coupled ferromagnetic insulator, one can realize the memory metamaterial by coupling the N‐FMR to the resonance of the metamaterial.…”

Ultrafast Multilevel Switching in Au/YIG/n‐Si RRAM

“…For example, operation speeds as fast as 300 and 100 ps were achieved in HfO x and Pt-SiO 2 based BRS RRAMs, respectively, [35][36][37] while the reliable multilevel control in BRS RRAMs was only obtained with operation speed of dozens or even hundreds of nanoseconds. [38][39][40] Besides the well-known magneto-optical memory applications for YIG, early in 1970, Bullock et al found a repeatable URS behavior in Si-doped YIG crystal. Therefore, it will be interesting to study the sub-nanosecond operating ability in a URS device, in which a typical high off/on resistance ratio may be able to host multilevel resistance states with ultrafast operation speed.…”

“…[38][39][40] Besides the well-known magneto-optical memory applications for YIG, early in 1970, Bullock et al found a repeatable URS behavior in Si-doped YIG crystal. [38][39][40] Besides the well-known magneto-optical memory applications for YIG, early in 1970, Bullock et al found a repeatable URS behavior in Si-doped YIG crystal.…”