Process-Gas-Influenced Anti-Site Disorder and Its Effects on Magnetic and Electronic Properties of Half-Metallic Sr2FeMoO6 Thin Films

Abstract

Anti-site disorder, arising due to the similar size of Fe and Mo ions in Sr2FeMoO6 (SFMO) double perovskites, hampers spintronic applicability by deteriorating the magnetic response of this double perovskite system. A higher degree of anti-site disorder can also completely destroy the half-metallicity of the SFMO system. To study the effects of different process gas conditions on the anti-site disorder, we have prepared a series of SFMO thin films on SrTiO3 (001) single-crystal substrate using a pulsed laser deposition (PLD) technique. The films are grown either under vacuum or under N2/O2 partial gas pressures. The vacuum-grown SFMO film shows the maximum value of saturation magnetization (MS) and Curie temperature (TC), signaling the lowest anti-site disorder in this series. In other words, there is a long-range Fe/Mo-O-Mo/Fe ferrimagnetic exchange in the vacuum-grown thin film, thereby enhancing the magnetization. Further, all the SFMO films show a semiconducting state with a systematic increase in overall resistivity with the increased anti-site disorder. The electrical conduction mechanism is defined by the variable-range hopping model at low temperatures. Raman spectra show a weak Fano peak, suggesting the presence of electron–phonon coupling in SFMO thin films. These results show the significance of the process gas in causing anti-site disorder, tuning the degree of this disorder and therefore its influence on the structural, magnetic, electrical, and vibrational properties of SFMO thin films.

Enhanced cation ordering, electron-spin-phonon interactions and Fano resonance in half-metallic Sr2FeMoO6 thin films

“…With the increase in the background gas pressure, the Full Width at Half Maxima (FWHM) starts increasing. This reduced crystallinity for SFMO films grown in oxygen and nitrogen gases, is consistent with our earlier observations of effects arising due to anti-site disorder in these films [27]. temperature.…”

“…Keeping the above-mentioned points in consideration, we have synthesized a series of SFMO thin films in different background conditions on LaAlO 3 -LAO (001) single-crystal substrate using Pulsed laser Deposition (PLD) technique. The depositions have been carried out in vacuum and in nitrogen and oxygen gases which varies the degree of cation ordering in SFMO films as per our earlier study [27]. Moreover, LAO is the best-suited substrate for the Raman spectroscopic studies on SFMO thin films.…”

Phase Separation in the Double Perovskite Sr2FeNbO6-δ

“…It should be noted that the ionic radii of iron and niobium in a sixfold environment almost coincide (0.67 Å and 0.66 Å, respectively), which is also realized for compounds with Mo and Fe [11]. Therefore, the authors of [11] suggest using thin films to obtain an ordered distribution of elements. The B-site ordering double perovskites has also been widely reported in room-temperature electrolysis, such as water splitting [12].…”

“…It was shown that the decoupling of phonon-glass and electron-crystal behaviors in oxides is possible by reducing thermal conductivity due to the induced dipolar glassy state as a result of relaxor ferroelectricity [10]. It should be noted that the ionic radii of iron and niobium in a sixfold environment almost coincide (0.67 Å and 0.66 Å, respectively), which is also realized for compounds with Mo and Fe [11]. Therefore, the authors of [11] suggest using thin films to obtain an ordered distribution of elements.…”