Half-metallic Chromium dioxide thin films for spintronic applications

CrO2 is a well-established half-metallic oxide with near perfect spin polarization -- known to have the highest spin polarization among all known materials theoretically as well as experimentally. This means that the conduction electrons in CrO2 have only one kind of spin i.e. conduction is due only to the majority spin electrons. Because of its high spin polarization, CrO2 stands as an ideal and one of the most attractive candidates for spin-electronic applications as well as of fundamental interests. The enormous potential of CrO2 is still untapped since thin film growth modes, interface/surface properties and various factors affecting them are not very well understood or, relatively unknown. Reported works confirm strained growth of (100) CrO2 films and strain free growth of (110) CrO2 films on iso-structural TiO 2 substrates investigated using X-ray diffraction. Superconducting quantum interference device (SQUID) and element specific X-ray magnetic circular dichroism (XMCD) techniques were employed to investigate the effect of this substrate-induced strain on the magnetic properties of the films. Magnetic tunnel junctions (MTJ) were fabricated with CrO2, Cr2O3 [natural oxide of Cr] as the thin insulating barrier and Co as the other ferromagnetic electrode using photolithography. I..V characteristics of this spin-electronic device are reported. Also, results on the low pressure chemical vapor deposition (CVD) growth of CrO2 and its comparison with standard growth technique under atmospheric pressure are reported.