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Calendar: ALS Calendar
Title: ALS-CXRO Seminar | Kangkang Wang
When: 02/13/2013 3:00 PM - 4:00 PM
Description: ALS-CXRO Seminar Series

Wed, February 13, 2013

Peter Fischer/Jinghua Guo

Presented by:
Kangkang Wang
Seagate Technologies

Room-temperature spin-polarized scanning tunneling microscopy of antiferromagnetic Mn3N2(001) nanopyramids

Antiferromagnets play a key role in spintronic applications owing to the exchange bias effect. As devices miniaturize in size and dimension, novel magnetic structures dramatically different from the bulk often emerge. Here we apply spin-polarized scanning tunneling microscopy (SP-STM) at room temperature to study the local magnetization of antiferromagnetic nitridenanostructures. Mn3N2(001) thin films have been grown on MgO(001) substrates using molecular beam epitaxy and transferred in-situ to a home-built SP-STM for magnetic imaging. Results[1] show that the surface consists of alternating chemically in-equivalent atomic terraces. Using SP-STM with dI/dV mapping, different layers can be clearly discriminated due to their different conductances. These differences in conductance are a result of not only the different chemical environments, but also the spin ordering and broken symmetry at the surface. Contrary to expectations, a layer-wise alternating surface anisotropy in these nanopyramids is observed. The presented study enables further investigations of the interplay between growth defects and the formation of intriguing antiferromagnetic domains.
In addition I will also talk about our recent developments on synchrotron x-ray scanning tunneling microscopy (SXSTM) at Argonne National Laboratory.[2] Using x-ray to excite core-level electrons while tunneling, SXSTM will potentially enable us to achieve elemental and chemical sensitivity at the atomic resolution.
[1] Kangkang Wang and Arthur Smith, Nano Letters 12, 5443 (2012).
[2] Volker Rose, Kangkang Wang, TeYu Chien, Jon Hiller, Daniel Rosenmann, John W. Freeland, Curt Preissner, Saw-Wai Hla, Synchrotron X-ray Scanning Tunneling Microscopy: Fingerprinting near to far field transitions on Cu(111) induced by synchrotron radiation, submitted to Advanced Functional Materials.
Location: 6-2202-CR(20)