Victoria L. Karner

β -NMR Investigation of the Depth-Dependent Magnetic Properties of an Antiferromagnetic Surface

By measuring the prototypical antiferromagnet α-Fe_{2}O_{3}, we show that it is possible to determine the static spin orientation and dynamic spin correlations within nanometers from an antiferromagnetic surface using the nuclear spin polarization of implanted ^{8}Li^{+} ions detected with β-NMR. Remarkably, the first-order Morin spin reorientation in single crystal α-Fe_{2}O_{3} occurs at the same temperature at all depths between 1 and 100 nm from the (110) surface; however, the implanted nuclear spin experiences an increased 1/T_{1} relaxation rate at shallow depths revealing soft-surface magnons. The surface-localized dynamics decay towards the bulk with a characteristic length of ε=11±1  nm, closely matching the finite-size thresholds of hematite nanostructures.

Microscopic Dynamics of Li+ in Rutile TiO2 Revealed by 8Li β-Detected Nuclear Magnetic Resonance

Ryan M. L. McFadden,1, 2, ∗ Terry J. Buck,3 Aris Chatzichristos,2, 3 Chia-Chin Chen,4 David L. Cortie,1, 2, 3, † Kim H. Chow,5 Martin H. Dehn,2, 3 Victoria L. Karner,1, 2 Dimitrios Koumoulis,6, ‡ C. D. Philip Levy,7 Chilin Li,8 Iain McKenzie,7, 9 Rotraut Merkle,4 Gerald D. Morris,7 Matthew R. Pearson,7 Zaher Salman,10 Dominik Samuelis,4, § Monika Stachura,7 Jiyu Xiao,1 Joachim Maier,4 Robert F. Kiefl,2, 3, 7 and W. Andrew MacFarlane1, 2, 7, ¶ 1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada 2Stewart Blusson Quantum Matter Institute, University of British Columbia, 2355 East Mall, Vancouver, BC V6T 1Z4, Canada 3Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada 4Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany 5Department of Physics, University of Alberta, 4-181 CCIS, Edmonton, AB T6G 2E1, Canada 6Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095, USA 7TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada 8Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai, P.R. China 200050 9Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada 10Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland (Dated: August 11, 2018)