|Title||beta-NMR Investigation of the Depth-Dependent Magnetic Properties of an Antiferromagnetic Surface|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Cortie, DL, Buck, T, Dehn, MH, Karner, VL, Kiefl, RF, Levy, CDP, McFadden, RML, Morris, GD, McKenzie, I, Pearson, MR, Wang, XL, MacFarlane, WA|
|Journal||PHYSICAL REVIEW LETTERS|
|Date Published||MAR 10|
By measuring the prototypical antiferromagnet alpha-Fe2O3, 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 Li-8(+) ions detected with beta-NMR. Remarkably, the first-order Morin spin reorientation in single crystal alpha-Fe2O3 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 epsilon = 11 +/- 1 nm, closely matching the finite-size thresholds of hematite nanostructures.