Thermal stability of exchange bias systems based on MnN

Recent Developments on MnN for Spintronic Applications

“…The electrical manipulation of the magnetic order with current pulses was observed over a broad temperature range between 160 K and 260 K. With increasing temperature, a more efficient switching of the magnetic order was observed, with a simultaneous reduction in the relaxation time for randomization of the magnetic order. The analysis of the magnetocrystalline anisotropy in Reference [24] and the quantitative analysis of the temperature-dependent relaxation dynamics both consistently point to an energy barrier of 0.5 eV to 0.7 eV for the grains that participate in the observed switching. This renders the magnetic order of MnN easily switchable with the spin Hall effect but at the expense of a rapid thermal relaxation back to a disordered equilibrium.…”

“…Thus, it seems like there is much more work to be done on MnN before our understanding of this intriguingly complex material is complete. [24]…”

“…Another key requirement for a given AF material to be considered as a candidate for device applications is that it must have a relatively high magnetocrystalline anisotropy. Sinclair et al [24] reported the first experimental measurement of the anisotropy constant of MnN in thin-film form from the measurement of the distribution of blocking temperatures in a MnN(t AF )/CoFe(2 nm) exchange-bias systems. A detailed description of the technique used can be found in Reference [25].…”

Anisotropy in antiferromagnets

“…From this data a median blocking temperature of 388K is observed which again is a value that would be usable in a device albeit with the limitation of the large film thickness. From the data and a knowledge of the grain size, which in this case was obtained from the Scherrer broadening of the X-ray lines, we have made an estimate of the effective anisotropy constant of MnN of KAF=7x10 4 ergs/cc [38]. Whilst this is a modest value compared to that for IrMn which has found to be as large as KAF=2.7x10 7 ergs/cc, nonetheless it is significant that a material with a tetragonal structure has been found to have sufficient anisotropy that, if grown with relatively large grain volumes, a significant exchange bias with the required level of thermal stability can be generated.…”

“…shows the blocking temperature curve for the sample provided to us by Meinert et al together with the film structure[38]. * now at Technical University of Darmstadt.…”