Interface effects, magnetic, and magneto-optical properties ofAl∕Co∕V∕MgO(100)structures

Abstract

The magnetic and magneto-optical properties of Al/ Co/ V / MgO͑100͒ structures and the influence of the Co/ V interface for different thicknesses of the Co and V layers have been studied experimentally. From the element-specific hysteresis loops obtained by x-ray magnetic circular dichroism ͑XMCD͒ at the Co and V L 3 edges we find that the V layers are magnetically polarized antiparallel to the Co layers and that magnetization reversal occurs at the same magnetic field in both layers. The effect of the V atomic volume and the relative thicknesses of V and Co layers on the magnetic moments of the V and Co atoms are also studied. Contrary to what might be expected, the atomic magnetic moments of the V and Co atoms do not depend on the V atomic volume, however they depend strongly on the thicknesses of the V and Co layers. From the trend in the Co and V atomic magnetic moments as a function of Co and V thicknesses and the absence of any spectroscopic evidence for the formation of a VCo alloy, a long-range spin polarization of the V atoms is proposed. The extracted magneto-optical ͑MO͒ constants of V and Co as a function of photon energy clearly evidence a large amount of polarization in the V films in agreement with the XMCD results, which is indicative of the magnetic coupling between Co and V. The experimental MO results and simulations also show the strong influence of these polarized V layers in the MO properties of the complete system. These results, given the absence of spectroscopic evidence for the formation of a VCo alloy, support a long-range magnetization of the V atoms and a reduction of the Co atomic magnetic moments.

Enhancement of induced V polarization due to rough interfaces in polycrystalline V/Fe/V trilayers

“…As can be observed, the loops exhibit opposite signs, indicating not only V polarization but also antiferromagnetic coupling be-tween Fe and V. It is worth noticing that both elements exhibit the same coercive and saturation fields, indicating Fe and V magnetizations are strongly coupled and directly related, as previously observed in Al/Co/V/MgO͑100͒ multilayers. 29 Furthermore, coercive and saturation fields are compatible with the SQUID observations at RT.…”

Matrix and interaction effects on the magnetic properties of Co nanoparticles embedded in gold and vanadium

“…Large V induced atomic magnetic moment coupled antiferromagnetically with reduced Co atomic magnetic moment has been reported at the V/Co interface of thin films. 60,61,[63][64][65][66][67] Assuming that this antiferromagnetic coupling holds in the case of Co nanoparticles in the V matrix, exchange bias (EB) effect has been investigated in the V system. Note that such an antiferromagnetic interface is expected to contribute to the magnetization with a linear law, especially at high magnetic fields.…”

“…50,51 Co nanoparticles have been embedded in metallic hosts such as Pt, 44 Nd, 52 Cu, 53 Mn, 54 Ag 55 and Au. 33 On the other hand, although there are several studies of Co/V multilayers, [56][57][58][59][60][61][62][63][64][65][66][67] as far as we know, the magnetic properties of Co NPs embedded in the metallic vanadium matrix have not been reported. We will firstly investigate the morphology of Co nanoparticles deposited on flat Si(100) surfaces and calculate the occupation in terms of coverage percentage of a monolayer.…”

Long-ranged magnetic proximity effects in noble metal-doped cobalt probed with spin-dependent tunnelling

“…This is to be contrasted with hot electron photoemission results, such as those of Pierce and Siegmann, who measured a 1 nm decay length through Cu, where electrons further from the Fermi level are probed [48]. The XMCD results cited in the introduction [2][3][4][5][6][7] also concern (primarily d-like) electrons over a wider energy window around the Fermi level. Our results here were obtained at low biases-10 mV for TMR and < 1 mV for the TSP-and so are very sensitive to what happens at the Fermi level.…”

“…More specialized methods therefore have to be brought to bear. Transition metal ferromagnets in contact with a noble metal [2,3], a transition metal [4], a spin glass [5], an actinide metal [6] and a dilute magnetic semiconductor [7][8][9][10] have been studied by x-ray magnetic circular dichroism (XMCD) methods. Those experiments used the fact that XMCD is able to separate the magnetic signal from different chemical elements [11].…”