The spin polarization of palladium on magneto-electric Cr 2 O 3 .

While induced spin polarization of a palladium (Pd) overlayer on antiferromagnetic and magneto-electric Cr ₂ O ₃ (0001) is possible because of the boundary polarization at the Cr ₂ O ₃ (0001), in the single domain state, the Pd thin film appears to be ferromagnetic on its own, likely as a result of strain. In the conduction band, we find the experimental evidence of ferromagnetic spin polarized in Pd thin films on a Cr ₂ O ₃ (0001) single crystal, especially in the thin limit, Pd thickness of around 1-4 nm. Indeed there is significant spin polarization in 10 Å thick Pd films on Cr ₂ O ₃ (0001) at 310 K, i.e. above the Néel temperature of bulk Cr ₂ O ₃ . While Cr ₂ O ₃ (0001) has surface moments that tend to align along the surface normal, for Pd on Cr ₂ O ₃ , the spin polarization contains an in-plane component. Strain in the Pd adlayer on Cr ₂ O ₃ (0001) appears correlated to the spin polarization measured in spin polarized inverse photoemission spectroscopy. Further evidence for magnetization of Pd on Cr ₂ O ₃ is provided by measurement of the exchange bias fields in Cr ₂ O ₃ /Pd(buffer)/[Co/Pd] _n exchange bias systems. The magnitude of the exchange bias field is, over a wide temperature range, virtually unaffected by the Pd thickness variation between 1 and 2 nm.
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