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Osheroff is most notable for his experimental work in condensed matter physics that demonstrated superfluidity in Helium-3. Osheroff and his colleagues found that Helium-3 became a superfluid at 0.0025 degrees above absolute zero. This was a surprising discovery because it was previously thought that only Helium-4 could become a superfluid. Osheroff's discovery helped to explain the properties of Helium-3 and led to new insights into the nature of superfluidity.