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prof.dr. J. Moodera: Interfaces, exchange effects and spin filtering - what happens then?

Wanneer:vr 06-09-2013 16:00 - 17:00
Waar:5113.0202

ABSTRACT

Information storage bit size and computing is inching towards molecular level. Spin transport in organic semiconductors (OS) has the potential in realizing this goal in a straightforward way. The charge and spin transport at OS and ferromagnetic metal interface, although complex, has the needed capabilities and potential for achieving molecular level spintronics. Spin tunneling through a few monolayers to thick films of some types of OS molecules show unexpected induced ferromagnetic and spin filter behavior at the ferromagnet/OS interfaces with a large induced surface anisotropy. Our experimental results along with density functional calculations describe these graphene fragment molecules as templates on ferromagnet surface to control the interface chemistry, magnetism and exchange coupling required for the stability and manipulation of information stored in individual molecules.

In the second part, we talk of an exchange gap in the Dirac surface states of a topological insulator (TI), necessary for observing the predicted unique features such as the topological magnetoelectric effect as well as to confine Majorana fermions, We d emonstrated proximity-induced FM in a TI, by creating thin film heterostructure of a ferromagnetic insulator EuS with TI thin films such as Bi2Se3 and Bi2Te3 surface without introducing defects in the material which can happen when doped with magnetic impurities . This approach of interfacial exchange interaction enables the creation of a ferromagnetic TI, superior to that when the TI is doped with say transition elements . This is a step forward in unveiling their exotic properties.

Many collaborators contributed to this work and research supported by NSF and ONR grants.

1. K. V. Raman et al., Nature 493, 509-513 (2013);

2. P. Wei et al., Phys. Rev. Lett. 110, 186807 (30 April 2013)