| Autor: |
Cheng, S. F., Woods, G. T., Bussmann, K., Mazin, I. I., Soulen, R. J., Carpenter, E. E., Das, B. N., Lubitz, P. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 5/15/2003, Vol. 93 Issue 10, p6847, 3p, 2 Graphs |
| Abstrakt: |
The pyrite Fe[SUB1-x]Co[SUBX]S[SUB2] (0.25≤x≤0.9) was predicted to be half metal, insensitive to Fe-Co disorder. To verify its half metallicity, we have grown single crystals of Fe[SUB1-x]Co[SUBx]S[SUB2] (x)=0.35, 0.5, 0.75, 0.9, and 1). Crystals of up to a few mm in size by temperature gradient (923-873 K) solution growth from Te melts, which showed high crystalline quality by scanning electron microscopy, x-ray diffraction, and magnetic measurements. A half-metallic magnetization of 1±0.03μ[SUBB] per Co atom was found for x=0.35-0.9. Point contact Andreev reflection measurements, however, showed spin polarization of 47%-61% with the maximum around x=0.5, well below predictions. Ferromagnetic resonance measurements give g∼2.08 with large intrinsic damping, which indicates a reduced half-metallicity. Inductively coupled plasma and energy dispersive x-ray spectroscopy results confirm a sulfur deficiency of &sim1.5%-10% [Fe,Co)S[SUB2-y],0.03≤y≤0.2] and small amounts of Te. Electronic structure calculations show the extra electron provided by Co substitution to FeS[SUB2] populates a sulfur-derived conduction band. Consequently, S deficiency and/or S site disorder are expected to affect the transport properties. This is consistent with the low polarization measurements and again indicates the importance of crystalline order in obtaining highly spin-polarized materials. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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