A critical analysis of the feasibility of pure strain-actuated giant magnetostrictive nanoscale memories

Abstract

Concepts for memories based on the manipulation of giant magnetostrictive nanomagnets by stress pulses have garnered recent attention due to their potential for ultra-low energy operation in the high storage density limit. Here we discuss the feasibility of making such memories in light of the fact that the Gilbert damping of such materials is typically quite high.We report the results of numerical simulations for several classes of toggle precessional and nontoggle dissipative magnetoelastic switching modes. Material candidates for each of the several classes are analyzed and forms for the anisotropy energy density and ranges of material parameters appropriate for each material class are employed. Our study indicates that the Gilbert damping as well as the anisotropy and demagnetization energies are all crucial for determining the feasibility of magnetoelastic toggle-mode precessional switching schemes. The roles of thermal stability and thermal fluctuations for stress-pulse switching of giant magnetostrictive nanomagnets are also discussed in detail and are shown to be important in the viability, design, and footprint of magnetostrictive switching schemes.

Nonreciprocal Magnetoacoustic Waves in Dipolar-Coupled Ferromagnetic Bilayers

“…Promising highly magnetostrictive materials are Fe-Co-Si-B [49,50], Fe-Ga [51], Fe-Ga-B [22,52], and Tb-Dy-Fe [53]. However, since highly magnetostrictive materials usually come with increased SW damping [54], achieving low values for IL might be more challenging for these materials than for our low-damping Py(20)/Au(5)/CoFeB(5) magnetic bilayer.…”

Analysis of Dynamic Magnetoelastic Coupling in Mechanically Driven Magnetoelectric Antennas

“…where θ is the angle between û and the direction of dominant static magnetization. Similar to the case of cubic crystals with dominant magnetization along a <100> direction, (20) indicates that the optimal applied stress is directed at an angle 45 • from the direction of dominant static magnetization.…”

“…For example, a substantial amount of research has been performed in this regard for high density, low power data storage applications [19]. However, these works were concerned with magnetic switching dynamics and stepped or pulsed mechanical stimuli [20] whereas our work deals with harmonic dynamics and stimuli. A substantial amount of research has also been performed assessing magnetization dynamics that are induced by surface acoustic wave mechanical stimuli for applications such as magnetic sensing [21] or spintronics [22].…”

Magneto Acoustic Spin Hall Oscillators

“…Magnetization of the free layer is controlled using an AC stress generated by the HBAR with magnetostriction effect [46][47][48][49]. In the presence of a uniaxial mechanical stress and external magnetic field in thex andẑ directions, effective magnetic field becomes H ef f =( H an m z + H ext )ẑ−( H d + H mech )m xx + H n .…”

“…The HBAR has a large time constant and acts as a delay element where the effective delay can be calculated as ∆t = (2Q n )/w rn , which is 330 ns at 3 GHz with a Q of 3000. Magnetization of the free layer is controlled using an AC stress generated by the HBAR with magnetostriction effect [46][47][48][49]. In the presence of a uniaxial mechanical stress and external magnetic field in the x and ẑ directions, effective magnetic field becomes…”