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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In order to permit magnetic exchangf, which essentially requires a bi-stable system, we propose a heat-assisted recording method, whereby both the ferromagnet FM and antiferromagnet AF are switched.

In order to investigate the possibility of “beating the superparamagnetic limit with exchange bias” Skumryev V. We demonstrate this principle for ferromagnetic cobalt nanoparticles of about 4 nm in diameter that are embedded in either a paramagnetic or an antiferromagnetic matrix.

Beating the superparamagnetic limit with exchange bias.

Yanes 2O. As a learned society, the EPS engages in activities that strengthen ties among the physicists in Europe. This behaviour is ascribed to the specific way ferromagnetic nanoparticles couple to an antiferromagnetic matrix. 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.

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.


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. 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.

Sign up for new issue notifications. Such a system is ideal for thermal stability since there is no energetically stable superpaamagnetic state, providing the antiferromagnetic shell is unchanged.

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On beating the superparamagnetic limit with exchange bias

However, with decreasing particle size the magnetic anisotropy energy per particle responsible for holding the magnetic moment along certain directions becomes comparable to the thermal energy. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness thr understanding of physics.

The Institute of Physics IOP is a leading scientific society promoting physics and bringing physicists together for the benefit of all. Chantrell 1 and O. Most applications rely on the magnetic order of the nanoparticles being beatkng with time.

Evans 1R. When this happens, the thermal fluctuations limiy random flipping of the magnetic moment with time, and the nanoparticles lose their stable magnetic order and become superparamagnetic.


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By continuing to use this site you agree to our use of cookies. Thus, the demand for further miniaturization comes into conflict with the superparamagnetism caused by the reduction of the anisotropy energy per particle: As a federation of National Physical Societies, the EPS studies issues of concern to all European countries relating to physics research, science policy superpqramagnetic education.

It has a worldwide membership of around 50 comprising physicists from all sectors, as well as those with an interest in physics.

Beating the superparamagnetic limit with exchange bias.

Evans et al EPL 88 Its publishing company, IOP Publishing, is a world leader in professional scientific communications. To find out more, see our Privacy and Cookies policy. Here we show that magnetic exchange coupling induced at the ljmit between ferromagnetic and antiferromagnetic systems can provide an extra source of anisotropy, leading to magnetization stability.

Mryasov 3R.