Occurrence of Rotation Domains in Heteroepitaxy

Grundmann, Marius; Böntgen, Tammo; Lorenz, Michael

doi:10.1103/physrevlett.105.146102

Cited by 76 publications

(61 citation statements)

References 46 publications

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“…When GST is grown on singular Si (top black curve) diffraction peaks of the same intensities are measured every 60° whereas the substrate has 3-fold symmetry (bottom gray curve). This is the evidence of GST twin domains formation due to weak interaction at the interface with the substrate 18 , as expected in the case of vdW epitaxy. In fact, by looking at the topography of this sample by atomic force microscopy (AFM), two triangular domains rotated of 180° are visible (white circles, Fig.…”

Section: Resultssupporting

confidence: 76%

Modulation of van der Waals and classical epitaxy induced by strain at the Si step edges in GeSbTe alloys

Zallo

Cecchi

Boschker

et al. 2017

Sci Rep

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The present work displays a route to design strain gradients at the interface between substrate and van der Waals bonded materials. The latter are expected to grow decoupled from the substrates and fully relaxed and thus, by definition, incompatible with conventional strain engineering. By the usage of passivated vicinal surfaces we are able to insert strain at step edges of layered chalcogenides, as demonstrated by the tilt of the epilayer in the growth direction with respect of the substrate orientation. The interplay between classical and van der Waals epitaxy can be modulated with an accurate choice of the substrate miscut. High quality crystalline GexSb2Te3+x with almost Ge1Sb2Te4 composition and improved degree of ordering of the vacancy layers is thus obtained by epitaxial growth of layers on 3–4° stepped Si substrates. These results highlight that it is possible to build and control strain in van der Waals systems, therefore opening up new prospects for the functionalization of epilayers by directly employing vicinal substrates.

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Section: Resultssupporting

confidence: 76%

Modulation of van der Waals and classical epitaxy induced by strain at the Si step edges in GeSbTe alloys

Zallo

Cecchi

Boschker

et al. 2017

Sci Rep

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“…This is consistent with Grundmann's theory that mismatch of surface rotational symmetries between film (C2mm) and substrate (C3m) creates domain rotations inside film. 17 C-type lattice alignment corresponds to the observed a and a 0 -domains. Note the adjacent two type-I sublattices of Al 2 O 3 exhibit reflection symmetry.…”

mentioning

confidence: 58%

Coexistence of epitaxial lattice rotation and twinning tilt induced by surface symmetry mismatch

Qiao

Xiao

Weber

et al. 2014

Applied Physics Letters

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Combined x-ray diffraction and first-principles studies of various epitaxial rutile-type metal dioxide films on Al 2 O 3 (0001) substrates reveal an unexpected rectangle-on-parallelogram heteroepitaxy. Unique matching of particular lattice spacings and crystal angles between the oxygen sublattices of Al 2 O 3 (0001) and the film(100) result in coexisted crystal rotation and lattice twinning inside the film. We demonstrate that, besides symmetry and lattice mismatch, angular mismatch along a specific crystal direction is also an important factor determining epitaxy. A generalized theorem has been proposed to explain epitaxial behaviors for tetragonal metal dioxides on Al 2 O 3 (0001).

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“…1(c) shows φ scans of the asymmetric Na 2 IrO 3 (202) and the YAO (101) and (121) reflections. From the mismatch between rotational symmetry C n and C m of film and substrate, which is C 1 for Na 2 IrO 3 and C 2 for YAO, one expects to observe two rotational domains, 27 i.e., two reflections in a φ scan of the Na 2 IrO 3 (202) reflection. Instead, we observe six reflections and assume that this increased number of rotational domains is either due to a mixed terminated surface of the YAO substrate containing half unit cell step heights 28 or other nearly fulfilled additional symmetries of the substrate surface.…”

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confidence: 99%

Mott variable-range hopping and weak antilocalization effect in heteroepitaxial Na2IrO3thin films

et al. 2013

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Iridate thin films are a prerequisite for any application utilizing their cooperative effects resulting from the interplay of strong spin-orbit coupling and electronic correlations. Here, heteroepitaxial Na 2 IrO 3 thin films with (001) out-of-plane crystalline orientation and well-defined in-plane epitaxial relationship are presented on various oxide substrates. Resistivity is dominated by a three-dimensional variable-range hopping mechanism in a large temperature range between 300 K and 40 K. Optical experiments show the onset of a small optical gap E go ≈ 200 meV and a splitting of the Ir 5d-t 2g manifold. Positive magnetoresistance below 3 T and 25 K shows signatures of a weak antilocalization effect.Transition-metal oxides containing 5d iridium ions allow for the observation of novel cooperative effects resulting from an interplay between strong spin-orbit coupling and electronic correlations. These iridates are promising candidates for high-T C superconductors, 1 spin liquids, 2-4 a novel J eff = 1/2 Mottinsulating ground state, 5,6 and topological insulators. 7-10 A rather recently studied iridate is the Mott-insulating layered compound Na 2 IrO 3 where edge-sharing IrO 6 octahedra form a honeycomb lattice within each Na 2 IrO 3 layer. 11 Theoretical studies of magnetic interactions in model Hamiltonians of A 2 BO 3 -type compounds 12,13 suggest spin liquid behavior in Na 2 IrO 3 . On the other hand, tight-binding model analyses and first-principles band structure calculations, 7,10,14 as well as density-matrix renormalization group calculations, 15 suggest Na 2 IrO 3 as a possible topological insulator. Both states of matter, however, promise possible application in fault-tolerant quantum computation. [16][17][18] Experimental efforts on Na 2 IrO 3 were so far limited to powder and single-crystalline samples. 11,19-22 Initially, from x-ray diffraction experiments a monoclinic C2/c unit cell for Na 2 IrO 3 was suggested. 11 More recent experiments however are more consistent with a C2/m unit cell. 19,20 Later experiments also confirm the presence of trigonal distortions of the IrO 6 octahedra and that structural disorder, i.e., stacking faults and Na/Ir site mixings, is common. The compound furthermore exhibits frustrated antiferromagnetic order below T N = 15 K with moments ordered collinearly in a zigzag pattern. 19-21 Furthermore, single-crystalline Na 2 IrO 3 has a small band gap. 22 Its temperature-dependent in-plane dc electrical resistivity follows a ρ ∝ exp[(T 0 /T ) 1/4 ] behavior between 100 and 300 K. 11 Such a ρ(T ) dependence is usually associated with three-dimensional Mott variable range hopping 23 of localized carriers.In this paper, we report on heteroepitaxial Na 2 IrO 3 thin films grown on (001) YAlO 3 , a-sapphire, and c-sapphire. Deposition of Na 2 IrO 3 thin films ultimately is a step towards future device applications of this material. Our heteroepitaxial films exhibit a clear epitaxial relation and an excellent (001) out-of-plane orientation. In magnetoresistance measurements we obs...

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Occurrence of Rotation Domains in Heteroepitaxy

Cited by 76 publications

References 46 publications

Modulation of van der Waals and classical epitaxy induced by strain at the Si step edges in GeSbTe alloys

Modulation of van der Waals and classical epitaxy induced by strain at the Si step edges in GeSbTe alloys

Coexistence of epitaxial lattice rotation and twinning tilt induced by surface symmetry mismatch

Mott variable-range hopping and weak antilocalization effect in heteroepitaxial Na2IrO3thin films

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