Recorded from IQC's NanoMRI conference 2015. The study of nanometer-scale magnetism is a vibrant sub-field of condensed matter physics concerned principally with magnetic phenomena in low-dimensional systems - phenomena that are often no observable in macroscopic systems. Its relevance to a variety of applications including precision sensing, high-density information storage and processing, and sensitive scanning probe techniques make the subject of particular technological interest. Martino Poggio discusses his teams recent efforts to use ultrasensitive force sensors in measurements of spin-physics on the nanometer-scale, in particular 1) nuclear magnetic resonance (NMR) measurements of nuclear spins in nanostructures and 2) magnetization measurements of individual nanomagents. Magnetic resonance force microscopy (MRFM) measurements of small nuclear spin ensembles reveal the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble[1]. Poggio demonstrates a method for measuring, manipulating and controlling the spin polarization of nanometer-scale spin ensembles[2]. These capabilities will be discussed in light of a recent proposal by Loss and colleagues predicting that the spin-orbit interaction (SOI) in semiconductor nanowires (NW) can be quantified through measurements of the relaxation rate of the constituent nuclear spins[3]. Specifically, their theory predicts that the nuclear T1 in a ballistic NW with Rashba and SOI has pronounced signatures, which depend on the strength of the SOI. Semiconductor NWs with strong SOI have attracted a great deal of recent interest due to the various topologically non-trivial electronic states that they are predicted to support. Given our demonstrated ability to do nanometer-scale NMR on semiconductor NWs, I will discuss ongoing measurements in this direction. Poggio concludes by presenting cantilever magnetometry measurements of the magnetisation of individual nanometer-scale magnets. We are interested in studying the magnetism of low-dimensional systems and in coming to a greater understanding of their magnetic configurations. Measurements on ferromagnetic nanotubes[4], single-crystal magnetic nanoparticles, and of nanostructures hosting magnetic skyrmions will be highlighted. [1] Herzog et al., Appl. Phys. Lett. 105, 043112 (2014) [2] Peddibhotla et. al., Nature Phys. 9, 631 (2013) [3] Zyuzin et al. Phys. Rev. 90, 195125 (2014) [4] Weber et al. Nano Lett. 12, 6139 (2012); Butcher et al. Phys. Rev. Lett. 111, 067202 (2013)

• published: 19 Aug 2015
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