22nd Magnetic Materials Center Seminar
July 10, 2006, 10:30
7th floor seminar room, Sengen
Spin Polarization studies of a variety of Heusler Alloys
Dhishan Kande, Ammanabrolu Rajanikanth
The spin polarization behavior of Cu2MnAl, Cu2MnIn, and Cu2MnSn, which were the foremost Heusler alloys to be studied, has been explored. These alloys have been chosen on account of their high Curie temperatures and because they do not show half-metallicity according to first principle calculations. So the experiment aims at verifying the accuracy of theoretical prediction. The spin polarization measurements for a number of full-Heusler alloys of the form Co2MnX(X=Sn, Al, Si) have been done and the corresponding quaternary Heusler alloys with composition lying in between the above ones have also been studied. The above family has been chosen on account of high curie temperatures and theoretical prediction of 100% spin polarization. The phase separated system showing high spin polarization of 63% is being characterized in detail by SEM, TEM, and EELS techniques. CoMnSn, which is a half-Heusler compound, has also been studied as it has a very high band-gap which may improve the chances of half-metallicity and thus give high spin polarization. The fact that Co2MnSn has shown a spin polarization of 60% makes the above system interesting to investigate. Some other compounds like Fe2MnGe and NiMnSn have also been explored for their spin polarization. Finally the possibility of making a hybrid Heusler alloy of the form Co1.5MnX which will combine the high Curie temperature of Full-Heusler compounds and the wide band-gap nature of half-Heusler compounds, keeping the L21 type of structure intact, is being attempted.