|Title:||Macroscopic Quantum Tunneling is Warming up|
|Group/Series/Folder:||Record Group 8.15 - Institute for Advanced Study|
Series 3 - Audio-visual Materials
|Location:||8.15:3 box 1.8|
|Notes:||IAS Asia Pacific Workshop on Condensed Matter Physics. Talk no. 23|
Title from title slide.
Host: Institute for Advanced Study.
Sponsor: The Collaborative Research Fund (CRF), The Research Grants Council (RGC).
Abstract: One of the most remarkable consequences of quantum physics is the finite probability of a particle tunneling through a barrier that according to classical physics is insurmountable. Quantum tunneling of microscopic particles is quite ubiquitous and is generally well understood. However, the extension of quantum tunneling to macroscopic objects remains an intriguing theoretical and experimental challenge. A promising route to macroscopic quantum tunneling is the use of magnetic nanoparticles with two stable states of reversed magnetization separated by an energy barrier. Classically, the energy required for hopping above the barrier is supplied by temperature; hence, the probability for reversal is strongly temperature dependent. On the other hand, quantum tunneling is temperature independent. In previous studies temperatures below 1 K were required to reliably identify magnetization reversal of magnetic nanoparticles dominated by macroscopic quantum tunneling, which complicated and limited considerably the study of this phenomenon. The speaker show clear evidence for macroscopic quantum tunneling up to 10 K by monitoring the magnetization reversal of individual strontium ruthenate (SrRuO₃) nanoparticles consisting of millions of atoms. We show that above 10 K the reversal is strongly temperature dependent and well described by classical models whereas below 10 K the reversal rate is practically temperature independent. This cross-over to macroscopic quantum tunneling at a temperature an order of magnitude higher than previously seen in individual magnetic nanoparticles provides exciting opportunities for the study of this phenomenon at new and larger length and temperature scales.
Duration: 39 min.
|Appears in Series:||8.15:3 - Audio-visual Materials|
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