On beating the superparamagnetic limit with exchange bias. R. F. L. Evans1, R. Yanes2, O. Mryasov3, R. W. Chantrell1 and O. Nature. Jun 19;() Beating the superparamagnetic limit with exchange bias. Skumryev V(1), Stoyanov S, Zhang Y, Hadjipanayis G, Givord D. Request PDF on ResearchGate | On beating the superparamagnetic limit with exchange bias | Interest in magnetic nanoparticles has increased.
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Chantrell 1 and O. Its publishing company, IOP Publishing, is a world leader in professional scientific communications. Whereas the cobalt cores lose their magnetic moment at 10 K in the first system, they remain ferromagnetic up to about K in the second.
Sign up for new issue notifications. As a learned society, the EPS engages in activities that strengthen ties among the physicists in Europe. Our results show that exchange-biased systems exhibit an increased energy barrier along the bias direction, with a corresponding decrease of the barrier in the opposite direction.
For systems with large values of the interfacial coupling, the ferromagnetic core is found to be unconditionally stable in the bias direction.
It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. It has a worldwide membership of around 50 comprising physicists from all sectors, as well as those with an interest in physics. Here we show that magnetic exchange coupling induced at the interface between ferromagnetic supedparamagnetic antiferromagnetic systems can provide an extra source of anisotropy, llmit to magnetization stability.
In order to permit magnetic recording, which essentially requires a bi-stable system, we propose a heat-assisted recording method, whereby both the ferromagnet FM and antiferromagnet AF are switched.
Such a system is ideal for thermal stability since there is no energetically stable reversed state, providing the antiferromagnetic shell is unchanged. However, with decreasing particle size the magnetic anisotropy energy per particle responsible for holding the magnetic moment along certain exchangee becomes comparable to the thermal energy.
Get permission to re-use this article. This behaviour is ascribed to the specific way ferromagnetic nanoparticles couple to an antiferromagnetic matrix. Mryasov 3R.
The Institute of Physics IOP is a leading scientific society promoting physics and bringing physicists together for the benefit of all.
As a federation of National Physical Societies, the EPS studies issues of concern to all European countries relating to physics research, science policy and education. Evans 1R. When this happens, the thermal fluctuations induce random flipping of the magnetic moment with time, and the nanoparticles lose their stable magnetic order and become superparamagnetic.
Interest in magnetic nanoparticles has increased in the past few years by virtue of their potential for applications in fields such as ultrahigh-density recording and medicine.
Thus, the demand for further miniaturization comes into conflict with the superparamagnetism caused by the reduction of the anisotropy energy per particle: Yanes 2O. Evans et al EPL 88 The European Physical Society EPS is a not for profit association whose members include 41 National Physical Societies in Europe, individuals from all fields of physics, and European research institutions.
Most applications rely on the magnetic order of the nanoparticles being stable with time. Click here to close this overlay, or press the “Escape” key on your keyboard.
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