Regensburg 2010 – scientific programme
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MA: Fachverband Magnetismus
MA 15: Magnetic Half-metals and Oxides I
MA 15.6: Talk
Wednesday, March 24, 2010, 11:30–11:45, H22
A Fermi-level-tuned half-metallic Heusler compound: Co2FeAl0.5Si0.5 — •Rong Shan1,2, Hiroaki Sukegawa1, Wenhong Wang1, Koichiro Inomata1, Benjamin Balke2, Gerhard H. Fecher2, and Claudia Felser2 — 1Magnetic Materials Center, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, 305-0047, Japan — 2Institute of Inorganic and Analytical Chemistry,Johannes Gutenberg - University, 55099 Mainz
Balke B. and Fecher G.H. et al. in our group made a theoretical prediction of Fermi level tuning in Heusler compounds, which suggested that the Fermi level of Co2Mn1−xFexSi and Co2FeAl1−xSix could be tuned to achieve the half-metallicity by the element substituting easily. However, to realize this prediction is a difficulty in experiment because of the perplexing relationship between the spin polarization of the quaternary Heusler compound and its structure disorder, resulting from the thermal treatment. Very recently, we confirmed Fermi level tuning in Heusler alloy Co2FeAl0.5Si0.5 (CFAS). Half-metallic band gap of CFAS was proved even at room temperature by the behavior of differential conductance of CFAS/(MgAl2)Ox/CoFe magnetic tunneling junctions with an unexplored crystalline (MgAl2)Ox barrier. CFAS exhibits the highest effective spin polarization (Peff) at 300 K and the weakest temperature dependence of Peff among all known half-metals. Further study shows that Peff of CFAS decays with increasing temperature (T) following T3/2 law perfectly, which indicates that the depolarization of CFAS is determined by spin wave excitation only.