Induced magnetization in thin epitaxial V films on Fe (100)

Abstract

Using spin-polarized secondary and Auger electron spectroscopy we find an induced magnetization in epitaxially grown V adlayers on Fe ͑100͒. Spin-dependent attenuation of the secondary electrons is quantitatively treated, following a model by Siegmann, to determine the adlayer magnetization. The first monolayer of V has a negative magnetic moment of Ϫ0.3Ϯ0.08 B per atom and thus couples antiferromagnetically to the Fe substrate. Subsequent V layers exhibit a positive magnetization. The reduction of the magnetization of Fe at the interface is found to be small. We determine an upper bound ͑M bulk ϪM interface ͒/M bulk Ͻ0.2 of the relative demagnetization of Fe upon V adsorption.Induced magnetic ordering in ''nonmagnetic'' thin films deposited on the surface of a ferromagnet has attracted considerable interest. A series of recent studies include Cr, Mn, V, as well as Ru, epitaxially grown on Fe ͑100͒. An induced magnetic moment unambiguously is found which in the coverage range of the first monolayer ͑ML͒ is oriented antiparallel to the magnetization of the substrate for the 3d-metal adlayers 1-5 and parallel for Ru. 6 For thicker adlayers an antiferromagnetic arrangement of adjacent ferromagnetic ͑100͒ sheets of about one monolayer thickness has been reported to occur in Cr ͑Ref. 2͒ and Mn, 3 whereas for V ͑Ref. 5͒ and Ru ͑Ref. 6͒ the moments basically are confined to the layers at the interface. Comparison of these experimental observations with computational predictions is a real challenge, however, if quantitative measurements of the induced magnetic moments are available. The only one in these systems to our knowledge is on Cr/Fe ͑100͒ by Turtur and Bayreuther 4 using alternating gradient magnetometry. It is the purpose of the present study to provide a further quantitative analysis of an induced magnetization in an adlayer on a surface of a ferromagnet. As a test system we choose V/Fe ͑100͒. Among the 3d metals V points towards less filled d bands and thus is an interesting candidate for studying effects of proximity to a ferromagnetic surface and altered atomic coordination.V at V/Fe interfaces of slabs and multilayers is predicted to carry an induced magnetic moment antiparallel to the Fe magnetization, 7-9 accompanied by a sizeable demagnetization of the Fe atoms at the interface. Computations of induced magnetizations in further V layers away from the interface also exist 7,8 and yield decreasing magnetic moments with increasing distance from the Fe interface. An induced moment in V antiparallel to the Fe magnetization is inferred from NMR measurements on ͑110͒ oriented multilayers. 10 Recently Walker et al. have found antiferromagnetic coupling of the first V monolayer to the Fe substrate and parallel alignment of the second one. 5 A number of Mössbauer studies on ͑110͒ oriented multilayers are claimed to confirm the calculated reduction of the Fe magnetization at the interface. 11 In this paper we present a quantitative study of thin V layers deposited on a bulk Fe ͑100͒ substrate. We use the combinatio...

Strong and Weak Interlayer Exchange Coupling in V/Fe Multilayers

“…Such behaviour reveals rather positive polarization of the rst atomic V interface layer and negative polarisation of the second atomic interface layer as reported in Ref. [22]. Furthermore, the observed dierent ranges and period of the AFM coupling strength across V could also depend on modication of the Fermi surface for ultrathin V(110) lms observed experimentally in Ref.…”

Electronic and magnetic structure of the (001) surfaces of V, Cr, and V/Cr

“…Since this early calculation was restricted to FM solutions, the AF state 3 was not found for the enlarged volumes.͒ Magnetism was reported for V monolayers ͑ML͒ on magnetic and nonmagnetic substrates [4][5][6][7] and thin films on Fe͑001͒. [8][9][10][11][12][13][14] Indeed, early calculations [15][16][17] suggested that the V͑001͒ surface might also be magnetic and experimental investigation with electron capture spectroscopy by Rau et al 18 seemed to confirm these findings. But measurements of thicker V͑001͒ films on Ag ͑Ref.…”

All-electron and pseudopotential study of the spin-polarization of the V(001) surface: LDA versus GGA

“…Vanadium is one of those paramagnetic metals 1 that can exhibit magnetism under certain conditions (loss of coordination, hybridization with a ferromagnet), due to its large paramagnetic susceptibility 2,3 . For instance, Akoh and Tasaki 4 have reported large localized magnetic moments in hyperfine particles of V, and several experimental groups have demonstrated the existence of an induced magnetization at the V interface for V overlayers on Fe substrates [5][6][7] and Fe/V multilayers [8][9][10] . Although these trends are clear, in other aspects there has not been consensus.…”