Ferrite memory materials

Greifer, A. P.

doi:10.1109/tmag.1969.1066649

Cited by 23 publications

(4 citation statements)

References 170 publications

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“…FC switching of millimetre-sized ferrite rings provided the basis for core memories in earlier computer technologies, prior to the advent of semiconductor-based devices. 5,6 More recently, FC states are being considered for NVRAM and related magnetoelectronic applications, based on nanosized bits. 1,2 The fundamental limit in the FC switching rate has been determined to be in the low picosecond range, orders of magnitude faster than switching speeds in present-day microprocessors.…”

Section: Introductionmentioning

confidence: 99%

Self-assembly and flux closure studies of magnetic nanoparticle rings

2011

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Thermoremanent magnetic nanoparticles (MNPs) can self-assemble into rings through dipolar interactions, when dispersed under appropriate conditions. Analysis of individual MNP rings and clusters by off-axis electron holography reveals bistable flux closure (FC) states at ambient temperatures, and their reversible switching by magnetic field gradients. We introduce a line-bond formalism to describe the coupling between MNPs.

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Section: Introductionmentioning

confidence: 99%

Self-assembly and flux closure studies of magnetic nanoparticle rings

2011

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“…Magnetic rings are well known to support bistable, vortex-like domains known as flux closure (FC), and can be used as binary data elements with minimal crosstalk between bits, permitting their 2D or 3D organisation into densely packed structures. This strategy was used many years ago using ferrite memory cores for data registry (2,3), prior to the advent of semiconductorbased devices. More recently, magnetic rings have been investigated as switches for non-volatile random-access memory (NVRAM) and other magnetoelectronic applications.…”

Section: Introductionmentioning

confidence: 99%

Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties

Wei

Tripp

Liu

et al. 2009

Supramolecular Chemistry

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Calixarenes can be used to promote the self-assembly of thermoremanent cobalt nanoparticles into bracelet-like rings below 100 nm in diameter. These kinetically stable assemblies are regulated by the equilibrium between enthalpic gain (dipoledipole and long-range van der Waals interactions) and entropic loss, analogous to the thermodynamic balance of forces governing supramolecular self-assembly. Examination of the Co nanoparticle rings by electron holography (an electron microscopy technique for imaging in-plane magnetic induction) reveals the existence of chiral flux closure (FC) domains at room temperature, comprising a 'racemic' mixture of clockwise and anticlockwise states. Furthermore, these FC polarisations can be reversed by applying out-of-plane magnetic pulses (H z ) in alternating directions. This switching behaviour has no known analogy at the macroscopic level, and may represent a uniquely nanoscale phenomenon.

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“…Therefore, not much detail can be found in the literature on the field dependence of the FMR frequency for this type of ferromagnetic spinel. What is known, is that our LiFe material should possess a cubic magneto-crystalline anisotropy 52,53 with (111) being an easy magnetisation axis (and (100) being the axis along which the resonance linewidth is minimal 54 ). However, the shapes of the hysteresis loops for the spheres (Fig.…”

Section: Magnetisation Properties Of Lithium Ferrite and Comparison T...mentioning

confidence: 99%

Cavity magnon polaritons with lithium ferrite and three-dimensional microwave resonators at millikelvin temperatures

et al. 2018

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Single crystal Lithium Ferrite (LiFe) spheres of sub-mm dimension are examined at mK temperatures, microwave frequencies and variable DC magnetic field, for use in hybrid quantum systems and condensed matter and fundamental physics experiments. Strong coupling regimes of the photon-magnon interaction (cavity magnon polariton quasi-particles) were observed with coupling strength of up to 250 MHz at 9.5 GHz (2.6%) with magnon linewidths of order 4 MHz (with potential improvement to sub-MHz values). We show that the photon-magnon coupling can be significantly improved and exceed that of the widely used Yttrium Iron Garnet crystal, due to the small unit cell of LiFe, allowing twice more spins per unit volume. Magnon mode softening was observed at low DC fields and combined with the normal Zeeman effect creates magnon spin wave modes that are insensitive to first order order magnetic field fluctuations. This effect is observed in the Kittel mode at 5.5 GHz (and another higher order mode at 6.5 GHz) with a DC magnetic field close to 0.19 Tesla. We show that if the cavity is tuned close to this frequency, the magnon polariton particles exhibit an enhanced range of strong coupling and insensitivity to magnetic field fluctuations with both first order and second order insensitivity to magnetic field as a function of frequency (double magic point clock transition), which could potentially be exploited in cavity QED experiments.

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Ferrite memory materials

Cited by 23 publications

References 170 publications

Self-assembly and flux closure studies of magnetic nanoparticle rings

Self-assembly and flux closure studies of magnetic nanoparticle rings

Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties

Cavity magnon polaritons with lithium ferrite and three-dimensional microwave resonators at millikelvin temperatures

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