Magnetic properties of sputtered Tb-Fe-Ga ternary compounds

The investigation on materials systems with perpendicular magnetic anisotropy (PMA) receives a large interest because of their applications in magnetic storage or in spintronic devices. Tb-Fe alloys were investigated because of their pretty large out-of-plane anisotropy constant. Recently, there have appeared reports about the influence of small amounts of Tb (< 1 at.%) in the magnetostriction of Fe-Ga alloys [1-3]. In other group of studies, the interest is the magnetic anisotropy of Tb-Fe-Ga compounds with a much higher Tb content [4-6]. We have studied how to control the magnetic properties of 250 nm thick Tb-Fe-Ga layers. Samples were cosputtered from two targets (TbFe2 and Fe3Ga) on glass substrates capped with a Mo layer. Two series of samples have been obtained depending on the power source (DC or pulsed) used in each target. Regardless of the power source used in the targets, we have found PMA in the Tb10Fe77Ga13 layers and an in-plane magnetic anisotropy for the Tb9Fe75Ga16. The Tb10Fe76Ga14 alloy has a magnetic anisotropy that depends on the power source. There is a clear PMA when using the DC power source in the TbFe2 target, whereas it changes to a weak PMA when using it in the Fe3Ga target. We have also found rotatable magnetic anisotropy in some samples. This means that the orientation of the magnetic domains depends on the direction of a previous applied magnetic field. This behavior can be used as a method for the determination of frauds produced by magnetic fields in devices such as water meters or hard disks [7]. References [1] T. Ma et al, Appl. Phys. Lett. 106, 112401 (2015). [2] W. Wu et al, Appl. Phys. Lett. 103, 262403 (2013). [3] L. Jiang et al, Appl. Phys. Lett. 102, 222409 (2013). [4] R. Ranchal et al, J. Alloys Compnd. 582, 839 (2014). [5] R. Ranchal and V. Gutiérrez-Díez, Thin Solid Films, 534, 557 (2013). [6] R. Ranchal et al, J. Alloys Compnd. 667, 262 (2016). [7] R. Ranchal, S. Fin, and D. Bisero. Spanish Patent, P201500492