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Please use this identifier to cite or link to this item: http://repository.li.mahidol.ac.th/dspace/handle/123456789/10950
Title: Josephson current in a double ferromagnetic layer SG/F 1/F 2/SG graphene sandwich
Authors: Bumned Soodchomshom
Tang, I.-M.
Rassmidara Hoonsawat
Mahidol University. Mahidol University International College.
Keywords: Graphene;Josephson current;Dirac particle;Double ferromagnetic barriers;SG/F/F/SG structure
Issue Date: 2010
Citation: Physica C: Superconductivity and its Applications. Vol. 470, No. 2 (2010), 123-128
Abstract: The Josephson current in a double ferromagnetic layer SG/F1/F2/SG graphene junction where the SG’s are graphene-based s-wave superconductors and the F1,2 are ferromagnetic layers of thicknesses d1,2 in which the exchange energies are Eex1,2, is studied. The Josephson current in this junction is composed of Cooper pairs formed by quasi particles which are massless Weyl–Dirac electrons. By switching the alignment of the two exchange fields, we find that the Josephson current in the junction can change from being in the π-state to being in the 0-state. For the case where the magnitudes of the exchange field strength are the same, it is seen that the phase difference dependence of the critical Josephson current in a parallel aligned junction indicated a cross over from a 0-state to π-state whenever the ferromagnetic barrier strength χex is equal to (n/2+0.25)π (with n=1, 2,…). The AP-junction for F1=F2 behaves as if it has no the magnetic barriers, like S/N/S junction. It is also seen that the temperature dependence of the (%) magneto-Josephson current ratio defined as the difference between the critical currents of the graphene-based P-junction and AP-junctions defined as, %PS∼(100%)x(IPc-IAPc)/IPc, is found to be oscillated under varying the exchange energies. The maximum value of %PS, (max)PS→−∞ as T→TC. The cause of these effects is the relativistic nature of the quasi particles in the graphene-based junctions.
URI: http://repository.li.mahidol.ac.th/dspace/handle/123456789/10950
metadata.dc.identifier.url: http://www.sciencedirect.com/science/article/pii/S0921453409007643
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