Direct Measurement of Rotatable and Frozen CoO Spins in Exchange Bias System of CoO/Fe/Ag(001)

Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
Physical Review Letters (Impact Factor: 7.51). 05/2010; 104(21):217204. DOI: 10.1103/PhysRevLett.104.217204
Source: PubMed


The exchange bias of epitaxially grown CoO/Fe/Ag(001) was investigated using x-ray magnetic circular dichroism and x-ray magnetic linear dichroism (XMLD) techniques. A direct XMLD measurement on the CoO layer during the Fe magnetization reversal shows that the CoO compensated spins are rotatable at thinner thickness and frozen at larger thickness. By a quantitative determination of the rotatable and frozen CoO spins as a function of the CoO film thickness, we find the remarkable result that the exchange bias is well established before frozen spins are detectable in the CoO film. We further show that the rotatable and frozen CoO spins are uniformly distributed in the CoO film.

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Available from: Yizheng Wu, Apr 09, 2015
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    • "Co spins are parallel to the surface plane, so that the coupling between Co and Fe spins at the interface is at 901. This 901 coupling has been reported for the (in-plane anisotropy) CoO/Fe interface on Ag(001)[14], where the AFM interface is formed by compensated Co spins. Such orthogonal coupling is, indeed, the most stable configuration when the exchange field of a FM layer interacts with a completely compensated AFM layer. "
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    • "While we have presented the preliminary magnetization data, to arrive at a clear picture, a host of more advanced measurements need to be performed on these heterostructures. For instance , to have a better understanding on the origin and nature of PEB, it is important to estimate the pinned interfacial uncompensated and rotatable (with the applied field) frozen spins using advanced interface specific techniques such as X-ray magnetic circular dischroism (XMCD) and X-ray magnetic linear dichroism (XMLD) [30] [31] [32]. In addition, exploring the nature of interfacial exchange coupling (parallel/antiparallel) using soft X-ray absorption spectroscopy [33] is essential. "
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