Growth, magnetism and ferromagnetic thickness gap in Fe films on the W(111) surface

Wu, Qiang; Zdyb, R.; Bauer, E.; Altman, Michael S.

doi:10.1103/physrevb.87.104410

Cited by 12 publications

(8 citation statements)

References 37 publications

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“…We can infer that the system will realize the d x 2 −y 2 + id xy superconducting state, which gives a fully gapped qusiparticle spectrum [21]. We remark that the obtained gap functions deviate a lot from the "standard" forms (which is usually assumed to be exclusively the NN or NNN pairings) that have been assumed in many previous literatures [13][14][15][16][17][18][19][20][21][22]. In the scenario of the "Eliashberg" equation, the order parameter is obtained self-consistently without presuming its structure in realspace or momentum-space.…”

Section: (A)mentioning

confidence: 86%

Possible singlet and triplet superconductivity on honeycomb lattice

Xiao¹,

Yu²,

Wang³

et al. 2016

EPL

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-We study the possible superconducting pairing symmetry mediated by spin and charge fluctuations on the honeycomb lattice using the extended Hubbard model and the random-phaseapproximation method. From 2% to 20% doping levels, a spin-singlet d x 2 −y 2 + idxy-wave is shown to be the leading superconducting pairing symmetry when only the on-site Coulomb interaction U is considered, with the gap function being a mixture of the nearest-neighbor and next-nearestneighbor pairings. When the offset of the energy level between the two sublattices exceeds a critical value, the most favorable pairing is a spin-triplet f -wave which is mainly composed of the next-nearest-neighbor pairing. We show that the next-nearest-neighbor Coulomb interaction V is also in favor of the spin-triplet f -wave pairing.Since the production of graphene (a honeycomb lattice of carbon atoms) in 2004 [1], the realization of superconductivity on the honeycomb lattice have attracted considerable interest [2][3][4][5]. Recently, the studies on the Ca-intercalated bilayer graphene and the graphene laminates observed superconductivities at 4 K [2] and 6.4 K [3] respectively. Furthermore, another recent experimental study also presented evidence for superconductivity in Lidecorated monolayer graphene with the transition temperature around 5.9 K [4]. On the theoretical side, the studies have been extended to models of interacting electrons on the honeycomb lattice, without necessarily concentrating on the parameter regions relevant to graphene, as other systems based on this geometry have been found [6]. Especially, nitrides β-MNCl (M=Hf,Zr) which are composed of alternate stacking of honeycomb layers have been observed to exhibit superconductivity with T c ∼ 15 K for Zr [7] and T c ∼ 25 K for Hf [8] by doping carriers. Various experimental results, including a weak isotope effect [9,10] and the T -linear specific heat [11], have pointed to an unconventional superconducting state, and the magnetic susceptibility measurements [12] suggest that the electron pairings are possibly mediated by magnetic fluctuations in these materials.Many theoretical studies based on the Hubbard model predict a superconducting order parameter with d x 2 −y 2 + id xy symmetry in the spin-singlet channel at half filling and low doping levels [13][14][15][16][17][18][19][20][21][22], while a recent study with the variational cluster approximation and the cellular dynamical mean field theory suggests that the dominant pairing is a spin-triplet with the p x + ip y symmetry [23]. A variational-Monte-Carlo (VMC) study shows that both the d x 2 −y 2 -wave and d x 2 −y 2 + id xy -wave are the possible superconducting pairing symmetry, but the state with d x 2 −y 2 -wave symmetry has the larger condensation energy [24]. Another quantum-Monte-Carlo study predicts that the favored state would have p x + ip y symmetry in the spin-triplet channel but at a large doping level (∼ 80%) [25]. Overall, the pairing symmetry of the possible superconductivity of the interacting electron ...

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Section: (A)mentioning

confidence: 86%

Possible singlet and triplet superconductivity on honeycomb lattice

Xiao¹,

Yu²,

Wang³

et al. 2016

EPL

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“…17,18 Despite the above promising applications, there are only a few studies reporting magnetic transition metals on the W(111) surface. 10,[19][20][21] In 1996, the structure and morphology of Co films on a clean W(111) surface were reported by Guan et al using low energy electron spectroscopy (LEED) and Auger electron spectroscopy (AES). Pseudomorphic Co films were grown at room temperature (RT) with thickness up to 4 PML.…”

Section: Introductionmentioning

confidence: 97%

Oxygen surfactant-assisted growth and dewetting of Co films on O-3 × 3/W(111)

Hsueh

Tsai

et al. 2013

Journal of Applied Physics

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Following the cyclic heating in oxygen and annealing, an oxygen-induced 3 Â 3 reconstruction was found on the W(111) surface. The growth, crystalline structure, thermal stability, and magnetism of Co ultrathin films deposited on the O-3 Â 3/W(111) surface were investigated. The Auger signal of the oxygen was always observable and nearly invariant after either Co deposition or annealing, indicating the role of the surfactant played by oxygen. Auger electron spectroscopy and scanning tunneling microscopy measurements revealed the 2-dimensional growth of Co on O-3 Â 3/W(111). Following the annealing procedures, the surfactant oxygen was always observed to float on the film surface while the Co film transformed to 3-dimensional islands with a wetting layer. In contrast to the thermodynamically stable wetting layer of 1 physical monolayer (PML) Co on clean W(111) between 700 and 1000 K, the oxygen surfactant led to a reduction of the wetting layer to %1/3 PML after thermal annealing. The 6 and 9.6 PML Co/O-3 Â 3/W(111) revealed a stable in-plane magnetic anisotropy. A 6-fold symmetry corresponding to the crystalline structure was observed in the in-plane angle-dependent magneto-optical Kerr effect measurement. V

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“…Photoelectron spin alignment represents an exploitable degree of freedom for probing both the structure and dynamics of matter. Spin-polarized electron bunches facilitate the imaging of magnetic domains in surfaces [1,2] and thin films [3][4][5], as well as the study of magnetization profiles in magnetic nanostructures [6][7][8]. Polarized electron beams are also instrumental in fundamental experiments addressing electron scattering and fluorescence emission from atoms and molecules [9][10][11][12], and even play a vital role in tests of the Standard Model with highenergy, electron-positron colliders [13].…”

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confidence: 99%