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Gambardella, Pietro; Claude, L.; Rusponi, Stefano; Franke, Katharina J.; Brune, Harald; Raabe, Jörg; Nolting, F.; Benčok, P.; Hanbicki, A. T.; Jonker, B. T.; Grazioli, Cesare; Veronese, M.; Carbone, C.

doi:10.1103/physrevb.75.125211

Cited by 36 publications

(28 citation statements)

References 45 publications

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“…We have presented a combined theoretical and experimental investigation of orbital magnetism and magnetic anisotropy of single Fe and Co adatoms on Rh͑111͒ and Pd͑111͒ substrates, complementing earlier results 4,21,30,73,74 of the same adatoms on Pt͑111͒. Table VI confronts the collected experimental and theoretical results.…”

Section: Discussionmentioning

confidence: 59%

Magnetocrystalline anisotropy energy of Co and Fe adatoms on the (111) surfaces of Pd and Rh

et al. 2010

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We performed a combined theoretical and experimental investigation of the orbital magnetism and magnetocrystalline anisotropy of isolated Co and Fe adatoms on Pd͑111͒ and Rh͑111͒. Theoretical calculations of the spin and orbital moments are based on ab initio spin-polarized density-functional theory ͑DFT͒ including a self-consistent treatment of spin-orbit coupling. The calculations use a slab model to represent the adsorbate/ substrate complex and allow for a complete structural relaxation leading to a strong inward displacement of the adatom and modest vertical and lateral relaxations in the substrate atoms. Compared to an idealized geometry where the atoms are kept on bulk lattice positions up to the surface, relaxation leads to a much stronger adatom/ligand hybridization. This is also reflected in the results for orbital moments and magnetocrystalline anisotropy energy ͑MAE͒. The enhanced hybridization leads to strong quenching of the adatom orbital moments but also to the formation of large induced spin and orbital moments in the substrate. As a consequence, we find that the substrate contribution to the MAE is much more important than estimated before on the basis of studies using an idealized geometry. We also find the surprising result that the MAE strongly depends on the adsorption site. The magnitude and even the sign of the MAE change for adatoms on face-centered cubic with respect to the ones on hexagonal close-packed hollow sites on the ͑111͒ surface. The dependence of the MAE on the combination of adatom and substrate has been analyzed in terms of the electronic structure, leading to a sound physical picture of the origin of the MAE. A fundamental problem, however, is the correct prediction of the size of the orbital moments of the adatoms. We suggest that this problem can be solved only via post-DFT corrections introducing an orbital dependence of the exchange potential. The theoretical results are compared to site-averaged, element-specific x-ray magnetic circular dichroism ͑XMCD͒ measurements. Lowtemperature XMCD spectra and magnetization curves reveal weak out-of-plane anisotropy for Fe adatoms on both substrates. Interestingly, Co adatoms on Rh͑111͒ present in-plane anisotropy with MAE of about −0.6 meV, contrary to the known out-of-plane anisotropy of Co on Pd͑111͒ and Pt͑111͒. The orbital to spin magnetic-moment ratio measured by XMCD shows that the Co adatoms present much stronger orbital magnetization components compared to Fe. The connection between orbital moments and MAE is discussed at the theoretical level including the contribution of the induced substrate magnetization.

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Section: Discussionmentioning

confidence: 59%

Magnetocrystalline anisotropy energy of Co and Fe adatoms on the (111) surfaces of Pd and Rh

et al. 2010

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“…Altogether, the x-ray absorption spectra of Mn-doped Ge indicate that the Mn moments order ferromagnetically below 150 K and therefore this is not a defect-induced magnetic ordering [23,24]. In comparison, the previous XMCD study on MBE grown epitaxial Ge 1-x Mn x does not show any remnant XMCD signal [32].…”

Section: Synchrotron X-ray Studies Of Mn-implanted Epitaxial Ge Thin mentioning

confidence: 57%

“…There are several XAS and XMCD studies on Mn-doped Ge epitaxial films [31][32][33]. However the possible presence of secondary phases, including oxides, makes it typically difficult to figure out the intrinsic magnetic moments of Mn in amorphous phase from those studies.…”

Section: Synchrotron X-ray Studies Of Mn-implanted Epitaxial Ge Thin mentioning

confidence: 99%

Ferromagnetism in Mn-implanted epitaxially grown Ge on Si(100)

et al. 2011

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We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultra high vacuum chemical vapor deposition using a mixture of germane (GeH 4 ) and methylgermane (CH 3 GeH 3 ) gases with a carbon concentration less than 1at%, and observed surface rms roughness of about 0.5 nm, as measured by atomic force microscopy.Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of about 16at%, 12at%, 6at% and 2at%. SQUID measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn]=2at%, is paramagnetic. X-ray absorption spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mnimplanted Ge films with [Mn]=16at% at 300 o C for up to 1200 seconds decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy (TEM) and synchrotron grazing incidence x-ray diffraction (GI-XRD) experiments show that the Mn-implanted region is amorphous, and we believe that it is this phase that is responsible for the ferromagnetism. This is supported by our observation that high temperature annealing leads to recrystallization and transformation of the material into a paramagnetic phase. * samaresh@physics.utexas.edu † banerjee@ece.utexas.edu 2

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“…To date, there are many reports on the Mn x Ge 1-x growth and characterizations by molecular beam epitaxy (MBE) (Park et al, 2002, Li et al, 2005, Jamet et al, 2006, Tsui et al, 2003, Ahlers et al, 2006a, Ahlers et al, 2006b, Bougeard et al, 2006, Devillers et al, 2007, Li et al, 2007, Park et al, 2001, Wang et al, 2008a, Pinto et al, 2005b, ion implantation (Park et al, 2005, Lin et al, 2008, Verna et al, 2006, D'Orazio et al, 2002, Liu et al, 2004, Lifeng et al, 2004, and bulk crystal growth (Cho et al, 2002, Biegger et al, 2007. We can divide them here, for an easier orientation, into two groups: those that cover fundermantal studies of phase formation, ferromagnetism, and transport properties (Park et al, 2002, Li et al, 2005, Majumdar et al, 2009a, Wang et al, 2008a, Gunnella et al, 2005, Liu et al, 2006, Jamet et al, 2006, Li et al, 2006b, Zhu et al, 2004, Miyoshi et al, 1999, Li et al, 2006a, Zeng et al, 2006, Cho et al, 2002, Liu and Reinke, 2008, Gambardella et al, 2007, Cho et al, 2006, Morresi et al, 2006, ...…”

Section: Overview Of the Mn Doped Gementioning

confidence: 99%