Malleability of uranium: Manipulating the charge-density wave in epitaxial films

Springell, R.; Ward, R. C. C.; Bouchet, Johann; Chivall, J.; Wermeille, D.; Normile, P. S.; Langridge, S.; Zochowski, S.W.; Lander, G. H.

doi:10.1103/physrevb.89.245101

Cited by 15 publications

(21 citation statements)

References 17 publications

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“…In a related system of charge transfer complex TTF:TCNQ there is clear signature of CDW transport in bulk single crystals, [25] films, [26,27] as well as in NWs. In a related system of charge transfer complex TTF:TCNQ there is clear signature of CDW transport in bulk single crystals, [25] films, [26,27] as well as in NWs.…”

Section: Discussionmentioning

confidence: 99%

Low temperature transport of a charge transfer complex nanowire grown with an electric field from the vapour phase

Basori

Raychaudhuri

2015

RSC Adv.

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Suspended Cu:TCNQ (Cu-tetracyanoquinodimethane) nanowires have been grown laterally from vapour phase connecting two electrodes (∼ 1.0µm gap) with and without the presence of external electric field applied between the electrodes during growth. Temperature and bias dependent conductance of these bridged nanowires have been investigated down to 40 K. It has been found that when the nanowire is grown in an electric field, its conductance gets enhanced significantly. The nanowires show a strong non-linear conductance beyond a threshold bias along with a linear conductance at low bias. Below 100 K, the bias dependent non-linear conductance with a threshold, can be fitted to modified Zener tunneling model for charge density wave transport in both types of nanowires, raising the possibility of onset of charge density wave type transport in the Cu:TCNQ nanowires. It has been proposed that the enhancement of the conductance in Cu:TCNQ nanowires when the growth is performed in the presence of electric field occurs due to better charge transfer as well as more ordered arrangements of TCNQ stacks during growth which is enabled by strongly anisotropic polarizability of the TCNQ moiety. This also modifies the parameters related to the non-linear conductance including the threshold value.

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Section: Discussionmentioning

confidence: 99%

Low temperature transport of a charge transfer complex nanowire grown with an electric field from the vapour phase

Basori

Raychaudhuri

2015

RSC Adv.

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“…Others put the focus on thin film [2] or epitaxial [3] samples that exhibit a substantially different behavior e.g. due to intrinsic strain, dominating surface effect, skin effect, etc.…”

Section: Diffraction and Charge-density-wave Transitionsmentioning

confidence: 99%

CDW-gaps, soft-phonons and physical transitions in bulk single crystal of alpha-Uranium

Marmeggi

Haen

Filhol

et al. 2015

J. Phys.: Conf. Ser.

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Abstract. An overview of three decades of studies of the low temperature structural behaviour of the bulk of alpha-Uranium (α-U) is presented. Combining high-resolution elastic and inelastic neutron scattering made it possible to observe and study, down to 5 K, the structural and lattice dynamical aspects of a series of three charge-density waves (CDWs) transition (43, 37 and 22 K). However at lower temperatures several physical quantities show anomalies such as a controversial superconductivity transition. This stresses the need for extra structural data down to very low temperatures. While this would be a challenge with neutrons due to fission sample heating, a new opportunity is offered by low temperature Laue diffraction with hard Xrays. For example a full locking of the periodic lattice distortion (PLD) can be expected related to the evolution of the CDW and/or the appearance of a SDW, this might help understand the physical behaviour of the material and clarify the role of sample impurities. Diffraction and charge-density-wave transitionsThe low-temperature phase of uranium metal (see [1] for a review) is called the alpha phase (α-U) and is stable below 935 K. We consider here the bulk material at ambient pressure and low temperature. Others put the focus on thin film [2] or epitaxial [3] samples that exhibit a substantially different behavior e.g. due to intrinsic strain, dominating surface effect, skin effect, etc. Thus the comparison is hazardous and a global discussion of both bulk and film results is out of our scope.α-U crystallizes in the orthorhombic system with space group Cmcm (A20) and exhibits a series of three periodic lattice distortions (PLDs) at low temperature. In the case of a metal these are known to be responsible for the lowering of the energy of the electron states thus opening a gap at the Fermi level. At ambient pressure a modulation wave vector (q) with respect to the equilibrium phase appears below T 0 ~ 43 K (: α 1 with ), changes to (: α 2 with <1/2, q y , q z >) at 37 K and then to (: α 3 with <1/2, 1/6, q z >) at 22 K. α-U is the only element, so far, which exhibits such a series of transitions. These true PLDs with ± q components were observed for the first time on the neutron Lauediffractometer S42 on α-U single crystals first and then on polycrystals [4,5]. The single crystals were produced by Fisher [6] using a grain coarsening method. In fact, white-beam neutron diffraction was

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“…However, it was not until 2008 that a theory was presented for the phonons (Bouchet, 2008), and this immediately suggested that the phonon anomaly should be suppressed by pressure -a prediction confirmed by experiments (Raymond et al, 2011) with ID28 at the ESRF using pressures up to 20 GPa. Later, actinide physics and chemistry experiments with thin films were successful in placing the [100] axis of -U under tensile stress (Springell et al, 2014), caused by interaction with the substrate, and the results were a CDW developing at 120 K, much higher temperature than in the bulk. The combination of theory and experiment showed the importance of the electron-phonon effects in the metal, and their momentum dependence.…”

Section: High-resolution Inelastic X-ray Scatteringmentioning

confidence: 99%

X-ray synchrotron radiation studies of actinide materials

Caciuffo¹,

Lander²

2021

J Synchrotron Rad

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By reviewing a selection of X-ray diffraction (XRD), resonant X-ray scattering (RXS), X-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic scattering (RIXS, NIXS), and dispersive inelastic scattering (IXS) experiments, the potential of synchrotron radiation techniques in studying lattice and electronic structure, hybridization effects, multipolar order and lattice dynamics in actinide materials is demonstrated.

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Malleability of uranium: Manipulating the charge-density wave in epitaxial films

Cited by 15 publications

References 17 publications

Low temperature transport of a charge transfer complex nanowire grown with an electric field from the vapour phase

Low temperature transport of a charge transfer complex nanowire grown with an electric field from the vapour phase

CDW-gaps, soft-phonons and physical transitions in bulk single crystal of alpha-Uranium

X-ray synchrotron radiation studies of actinide materials

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