Antiferromagnetism in Cr3Al and relation to semiconducting behavior
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Boekelheide, Zoe; Saerbeck, Thomas; Stampfl, Anton; Robinson, Robert; Stewart, Derek; Hellman, Frances
Antiferromagnetism and chemical ordering have both been previously suggested as causes of the observed semiconductorlike behavior in Cr3Al. Two films of Cr3Al(001)/MgO(001) were grown under different conditions to achieve different types of chemical ordering and electronic properties: one X-phase structure (semiconducting) and one C11b structure (metallic). The films were investigated by x-ray and neutron diffraction. Both films show commensurate antiferromagnetic order, with a high Néel temperature greater than 578 K, showing that the antiferromagnetism in Cr3Al is quite robust. Density-functional theory calculations were performed and it was shown that the well-known antiferromagnetic pseudogap in the density of states occurs for all types of chemical ordering considered. The conclusion of these studies is that the antiferromagnetism causes a pseudogap in the density of states, which is a necessary condition for the semiconductorlike transport behavior; however, that antiferromagnetism is seen in both metallic and semiconducting Cr3Al samples shows that antiferromagnetism is not a sufficient condition for semiconducting behavior. Chemical ordering is equally important.
American Physical Society
chromium; aluminum; alloy; antiferromagnetic; Cr3Al; electronic structure; x-ray; neutron diffraction; density functional theory
Previously Published As
Z. Boekelheide, T. Saerbeck, A. P. J. Stampfl, R. A. Robinson, D. A. Stewart, F. Hellman, Phys. Rev. B, 85, 094413 (2012)