Augmented MR of half-metallic ferromagnetic CrO2 based thin films & spin-controlled device in SWCNT-FET architecture

Abstract

Spin-controlled device in single-walled carbon nanotube-field effect transistor (SWCNT-FET) architecture are patterned by the combinatorial lithographic techniques that are made-up of the chromium oxides electrodes comprising of half-metal CrO₂ that is ferromagnetic in nature. Chromium oxides thin films were deposited over isostructural rutile-type-tetragonal TiO₂ layers on SiO₂/Si substrates. The as-deposited thin films consisted of the chromium-di-oxide (CrO₂) as the dominant phase along with the minor phase of antiferromagnetic Cr₂O₃. We report on the elaborate vibrational bands analysis of CrO₂ in the 2D thin film configuration based on Fourier transform infrared spectroscopic (FTIR) characterization. In the X-ray photoelectron spectroscopy (XPS) studies, we mention surface bonding elements of chromium oxides thin films along with the comprehensive description of different states. Magnetic force microscopic (MFM) images revealed the magnetic grain size of ∼235 nm in the chromium oxides thin films. Electrical & magnetoresistive studies confirmed the dominance of intergranular tunnelling mechanism along with an MR % = 40 % at T = 290 K. Spin-controlled device has been patterned by the electron beam lithography (EBL) by employing chemical etching technique in case of half-metal CrO₂ for the first time. We demonstrate the gate-dependent MR % in these spin-controlled devices of +60 % and -79 % under out-of-pane geometry of H = 0.1 T & H = 0.5 T at the temperature of T = 290 K, respectively.