Hydrogen-induced changes of the local structure in Fe/V (001) superlattices

Burkert, Till; Miniotas, A.; Hjörvarsson, Bjørgvin

doi:10.1103/physrevb.63.125424

Cited by 24 publications

(15 citation statements)

References 29 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…29,30 This latter type of insertion has been described as unstable against a phase transition toward the ␤ phase of vanadium according to EXAFS data. 13 We note that in this ␤ phase of V 2 H the O site is highly distorted, being the H atom no longer aligned with the V atoms in the plane. Such local structure resembles the triangular configuration obtained as the ground state in the H-loaded V dimer.…”

Section: Bulk Environmentsmentioning

confidence: 98%

“…The vanadium layers are also suggested to undergo a structural phase transition to the ␤ phase of vanadium hydride as increasing the H content, according to the extended x-ray absorption fine structure ͑EXAFS͒ data. 13 On the theoretical side concerning Fe/V systems, most of the studies have focused on the magnetic profiles in multilayers, 14,15 and few of them have considered the presence of H. Ostanin et al 16 using full-potential linear muffintin orbital ͑FP-LMTO͒ studied the magnetic behavior at the interface and the resistivity as a function of the H concentration in the V layer. The moment at the interface is supposed to decrease due to the important tetragonal distortion subsequent to the H absorption, although structural relaxation was not considered.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Interplay between structure and magnetism in hydride iron-vanadium systems

2008

View full text Add to dashboard Cite

The structural and electronic properties of dimers, bulk, and alloys of Fe and V upon loading with hydrogen have been investigated using the density-functional method Spanish Initiative for Electronic Simulation of Thousand of Atoms. We have calculated the hydrogen-induced modifications of both the geometrical structure and the magnetic properties, which have been found to be closely related to each other. The general trends derived from our results are in good agreement with those found in the experimental characterizations of hydrogen-loaded Fe/V multilayer systems. In particular, we have found that hydrogen prefers a V environment when inserted in the alloy systems at high concentration; it occupies octahedral positions leading to a strong anisotropic expansion of the lattice accompanied by an increase in the local Fe magnetic moments. We have found that the main trends obtained in the extended systems were already present in the most stable geometrical and spin isomers of the freestanding FeVH clusters.

show abstract

Section: Bulk Environmentsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Interplay between structure and magnetism in hydride iron-vanadium systems

2008

View full text Add to dashboard Cite

show abstract

“…7 The difference in H -H interaction energies is probably caused by a different interstitial site occupancy, i.e., T in case of biaxial tensile strain and O z in case of biaxial compressive strain. 8 This is not unreasonable considering that the site occupancy in V is very sensitive to applied strain. 9 For Fe/ V it means that the in-plane compression of the V layers and the corresponding elongation of the out-ofplane axis open up the lattice for population of the O z sites.…”

Section: Introductionmentioning

confidence: 99%

Effect of biaxial elastic constraints onH−Hinteractions in ultrathin vanadium

Olsson

Hjörvarsson

2005

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

The hydrogen ͑H͒ solubility isotherms and the relative partial enthalpy-and entropy of H in a MoV / V͑001͒ superlattice in the range 0 ഛ ͓H/V͔ ഛ 1 ͓atomic ratio͔ are addressed. The difference in solubility between MoV and V assures that H only resides in the 22Å thick V layers, and the use of MoV instead of Mo increases the range of reversibility of the uptake, for the actual strain state. The biaxial elastic constraints, imposed by the H-free layers and the substrate, are shown to have a big influence on the H -H interaction. At low H content, the mean H -H interaction is close to zero, while for ͓H/V͔ 0.25, the interaction becomes attractive. We show that for a film constrained to expand in one dimension, the elastic dipole interaction is zero when the H-induced local strain field is isotropic, whereas for an anisotropic local strain field the interaction energy can be attractive, if the strain axes are parallel aligned with the direction of the expansion. Based on the symmetries of the respective local strain fields, we interpret the onset of the attractive H -H interaction at ͓H/V͔Ϸ0.25 as a self-induced change of H site occupancy, from tetrahedral to octahedral sites.

show abstract

“…In fact, here we find that a modification of the V lattice volume of 5% corresponds to a change of resistivity by approximately a factor of 10. Recently, Burkert et al 12 found that the average expansion of the out-of-plane lattice parameter of V in Fe/ V multilayers loaded with 50% H is close to 5%. They also found that the in-plane lattice parameter was not modified by H loading, leading to a volume expansion close to 5%.…”

Section: Resultsmentioning

confidence: 99%

Role of volume versus defects in the electrical resistivity of lattice-distorted V(001) ultrathin films

et al. 2007

View full text Add to dashboard Cite

4 nm thick V layers grown by triode sputtering on MgO͑001͒ single crystals and capped with MgO exhibit a perfect epitaxy accompanied by a tetragonal distortion and an unexpected volume compression that increases with the V deposition temperature. The electrical resistivity follows a deposition temperature dependence with these structural modifications, decreasing by an order of magnitude across the temperature range studied. Total energy ab initio calculations rule out electronic structure changes and/or oxygen interface diffusion as responsible for the structure variation. Calculations of the ballistic conductance for the epitaxial V films do not reproduce the resistivity-volume correlation, implying a diffusive electron transport mechanism in the films, despite their high crystallinity. Instead, we assign the origin of the electrical behavior to the presence of growth induced defects in the V lattice, whose density is higher in films deposited at low temperature, and decreases as deposition temperature increases. These results extend the previous findings in volume expanded H loaded Fe/ V and Mo/ V superlattices to simpler structures where the H content is negligible and, additionaly, all the electronic transport is confined within the V film.

show abstract

Hydrogen-induced changes of the local structure in Fe/V (001) superlattices

Cited by 24 publications

References 29 publications

Interplay between structure and magnetism in hydride iron-vanadium systems

Interplay between structure and magnetism in hydride iron-vanadium systems

Effect of biaxial elastic constraints onH−Hinteractions in ultrathin vanadium

Role of volume versus defects in the electrical resistivity of lattice-distorted V(001) ultrathin films

Contact Info

Product

Resources

About