1,363 research outputs found
Effects Of Stress On Electron Emission From Nanostructured Carbon Materials
The electron field emission from a graphite like amorphous carbon film was investigated. Threshold fields as low as 8 V/νm were observed at an assisting energy of 400eV. The field emission characteristics of the films were explained in terms of the high sp2 concentration, and the high intrinsic compressive stress modifying the electronic band structure of the film/graphitic nanostructures.21417101714McKenzie, D.R., Muller, D., Pailthope, B.A., (1991) Phys. Rev. Lett., 67, p. 773Schwan, J., Ulrich, S., Theel, T., Roth, H., Ehrhardt, H., Becker, P., Silva, S.R.P., (1997) J. Appl. Phys., 82, p. 6024Lifshitz, Y., Kasi, S.R., Rabalais, J.W., Eckstein, W., (1990) Phys. Rev. B, 41, p. 10468Robertson, J., (1993) Diamond Relat. Mater., 2, p. 984Lacerda, R.G., Hammer, P., Lepienski, C.M., Alvarez, F., Marques, F.C., (2001) J. Vac. Sci. Technol. A, 19, p. 971Bhattacharyya, S., Subramanyam, S.V., (1997) Appl. Phys. Lett., 71, p. 632Kilic, C., Mehrez, H., Ciraci, S., (1998) Phys. Rev. B, 58, p. 7872Uher, C., Hockey, R.L., Ben-Jacob, E., (1987) Phys. Rev. B, 35, p. 4483Satyanarayana, B.S., Hart, A., Milne, W.I., Robertson, J., (1997) Appl. Phys. Lett., 71, p. 1430Carey, J.D., Forrest, R.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 2339Illie, A., Ferrari, C., Yagi, T., Robertson, J., (2000) Appl. Phys. Lett., 76, p. 2627De Lima M.M., Jr., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Hoffman, R.W., (1966) Physics of Thin Films, 3, pp. 211-273. , edited by G. Hass and R. E. Thun (Academic, New YorkCarey, J.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 347Hammer, P., Victoria, N.M., Alvarez, F., (2000) J. Vac. Sci. Technol. A, 18, p. 2277Lifshitz, Y., Lempert, G.D., Grossman, E., Avigal, L., Uzan-Saguy, C., Kalish, R., Khlik, J., Rabalais, J.W., (1995) Diamond Relat. Mater., 4, p. 318Fallon, P.J., Veerasamy, V.S., Davis, C.A., Robertson, J., Amaratunga, G.A.J., Milne, W.I., Koskinen, J., (1993) Phys. Rev. B, 48, p. 4777Ahuja, R., Auluck, S., Trygg, J., Wills, J.M., Eriksson, O., Johansson, B., (1995) Phys. Rev. B, 51, p. 4813Reynolds, W.N., Goggin, P.R., (1960) Philos. Mag., 5, p. 1049Lynch, R.W., Drickamer, H.G., (1966) J. Chem. Phys., 44, p. 181Chaumet, P.C., Dufour, J.P., (1998) J. Electrost., 43, p. 145Hryd, R., Charlier, A., McRae, E., (1997) Phys. Rev. B, 55, p. 682
A new non-Fermi liquid fixed point
We study a new exchange interaction in which the conduction electrons with
pseudo spin interact with the impurity spin . Due to the
overscreening of the impurity spin by higher conduction electron spin, a new
non-trivial intermediate coupling strength fixed point is realized. Using the
numerical renormalization group (NRG), we show that the low-energy spectra are
described by a non-Fermi liquid excitation spectrum. A conformal field theory
analysis is compared with NRG results and excellent agreement is obtained.
Using the double fusion rule to generate the operator spectrum with the
conformal theory, we find that the specific heat coefficient and magnetic
susceptibility will diverge as , that the scaling dimension of an
applied magnetic field is , and that exchange anisotropy is always
relevant. We discuss the possible relevance of our work to two-level system
Kondo materials and dilute cerium alloys, and we point out a paradox in
understanding the Bethe-Ansatz solutions to the multichannel Kondo model.Comment: Revised. 20 page
Personality Expression in Body Motion Dynamics:Enactive, Embodied and Complex Systems Perspectives
We explored personality expression through body motion using enactive/complex systems perspectives. We invited 105 adults (aged 18-33, 70% women) to talk for 15-minutes about three self-referencing topics (introduction, bodily perception/sensory life, socio-emotional life). A video frame-by-frame differentiation method provided time-series to perform Recurrence Quantification Analysis (RQA), extracting four measures (Determinism/Entropy/Laminarity/MeanLine). Multilevel models linked Big-Five traits (IPIP-NEO-120) to embodied dynamics. Neuroticism predicted lower determinism and fluctuating dynamics when talking about bodily perception/sensory life and socioemotional life; less complexity and stability when talking about socioemotional life, and post-task negative affect. Extraversion predicted regular/deterministic dynamics when talking about bodily perception/sensory life. Conscientiousness predicted less deterministic and more variability. Agreeableness predicted low post-task negative affect. The results are discussed integrating enactive/complexity, and personality perspectives
Anderson-Yuval approach to the multichannel Kondo problem
We analyze the structure of the perturbation expansion of the general
multichannel Kondo model with channel anisotropic exchange couplings and in the
presence of an external magnetic field, generalizing to this case the
Anderson-Yuval technique. For two channels, we are able to map the Kondo model
onto a generalized resonant level model. Limiting cases in which the equivalent
resonant level model is solvable are identified. The solution correctly
captures the properties of the two channel Kondo model, and also allows an
analytic description of the cross-over from the non Fermi liquid to the Fermi
liquid behavior caused by the channel anisotropy.Comment: 23 pages, ReVTeX, 4 figures av. on reques
Orbital Kondo behavior from dynamical structural defects
The interaction between an atom moving in a model double-well potential and
the conduction electrons is treated using renormalization group methods in
next-to-leading logarithmic order. A large number of excited states is taken
into account and the Kondo temperature is computed as a function of
barrier parameters. We find that for special parameters can be close to
and it can be of the same order of magnitude as the renormalized
splitting . However, in the perturbative regime we always find that
T_K \alt \Delta with a T_K \alt 1 {\rm K} [Aleiner {\em et al.}, Phys.
Rev. Lett. {\bf 86}, 2629 (2001)]. We also find that remains
unrenormalized at energies above the Debye frequency, .Comment: 9 pages, 9 figures, RevTe
A Peer-reviewed Newspaper About_ Datafied Research
An examination of the implications of datafication for research: to investigate and propose actions that push against the limits of today’s pervasive quantification of life, work, and play.
Publication resulting from research workshop at School of Creative Media, City University of Hong Kong, organised in collaboration with School of Creative Media, City University of Hong Kong, and transmediale festival of art and digital culture, Berlin
Multi-Channel Kondo Necklace
A multi--channel generalization of Doniach's Kondo necklace model is
formulated, and its phase diagram studied in the mean--field approximation. Our
intention is to introduce the possible simplest model which displays some of
the features expected from the overscreened Kondo lattice. The conduction
electron channels are represented by sets of pseudospins \vt_{j}, , which are all antiferromagnetically coupled to a periodic array of
|\vs|=1/2 spins. Exploiting permutation symmetry in the channel index
allows us to write down the self--consistency equation for general . For
, we find that the critical temperature is rising with increasing Kondo
interaction; we interpret this effect by pointing out that the Kondo coupling
creates the composite pseudospin objects which undergo an ordering transition.
The relevance of our findings to the underlying fermionic multi--channel
problem is discussed.Comment: 29 pages (2 figures upon request from [email protected]), LATEX,
submitted for publicatio
The 2-Channel Kondo Model I: Review of Experimental Evidence for its Realization in Metal Nanoconstrictions
Certain zero-bias anomalies (ZBAs) in the voltage, temperature and magnetic
field dependence of the conductance of quenched Cu point contacts
have previously been interpreted to be due to non-magnetic 2-channel Kondo
(2CK) scattering from near-degenerate atomic two-level tunneling systems (Ralph
and Buhrman, 1992; Ralph et al. 1994), and hence to represent an experimental
realization of the non-Fermi-liquid physics of the T=0 fixed point of the
2-channel Kondo model. In this, the first in a series of three papers
(I,II,III) devoted to 2-channel Kondo physics, we present a comprehensive
review of the quenched Cu ZBA experiments and their 2CK interpretation,
including new results on ZBAs in constrictions made from Ti or from metallic
glasses. We first review the evidence that the ZBAs are due to electron
scattering from stuctural defects that are not static, but possess internal
dynamics. In order to distinguish between several mechanisms proposed to
explain the experiments, we then analyze the scaling properties of the
conductance at low temperature and voltage and extract from the data a
universal scaling function . The theoretical calculation of the
corresponding scaling function within the 2CK model is the subject of papers II
and III. The main conclusion of our work is that the properties of the ZBAs,
and most notably their scaling behavior, are in good agreement with the 2CK
model and clearly different from several other proposed mechanisms.Comment: 35 pages RevTeX, 19 encapsulated postscript figures; this final
published version features two additional authors, an additional section
reviewing recent experiments on Ti nanoconstrictions that agree very well
with the 2-channel Kondo model, 6 new figures (and is much shorter the
previous 53 page version, due to reformatting
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