From Superparamagnetism to Macroscopic Quantum Tunneling with Individual Nanostructures of SrRuO3

The interest in magnetization reversal in nanostructures mainly focuses on two phenomena: the superparamagnetic behavior at a temperature range below the Curie temperature and the expected crossover between thermally-activated reversal to reversal dominated by macroscopic quantum tunneling at sufficiently low temperatures. Here we explore both phenomena by monitoring individual reversals in nanostructures of SrRuO₃ and obtain novel insight of both phenomena. In particular, we show for the first time the applicability of the Langevin equation to superparamagnetic fluctuations of an individual volume [1] and we find compelling indication for magnetization reversal dominated by macroscopic quantum tunneling below a record high temperature of  10 K [2].

References

1. O. Sinwani, J. W. Reiner, and L. Klein (2014). Monitoring superparamagnetic Langevin behavior of individual SrRuO₃ nanostructures. Phys. Rev. B 89 020404(R).
2. O. Sinwani, J. W. Reiner, and L. Klein (2012). Indication for macroscopic quantum tunneling below 10 K in nanostructures of SrRuO₃. Phys. Rev. B 86 100403(R).