Proximity effect in Co2MnGe /V/ Co2MnGe trilayers

We have studied the superconducting proximity effect in thin film trilayer systems combining the ferromagnetic Heusler compound Co2MnGe with superconducting V. The thickness dependence of our Co2MnGe/V/ Co2MnGe trilayers with variable thicknesses of the V and the Co2MnGe layers is well described by the theoretical models developed by Radović and Tagirov. We determine a superconducting correlation length ξF in the Co2MnGe layers of about 2.7 nm, which is exceptionally large when compared to other ferromagnets. We attribute this interesting feature to the spin glass type of magnetic order, which occurs in very thin layers of the Co2MnGe Heusler phase.