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Titolo: CHIRAL MELTING OF THE SI(113)(3X1) RECONSTRUCTION
Autore: ABERNATHY DL; SONG S; BLUM KI; BIRGENEAU RJ; MOCHRIE SGJ;
 Indirizzi:
 ESRF,BP 220 F38043 GRENOBLE FRANCE MIT CAMBRIDGE MA 02139
 Titolo Testata:
 Physica. B, Condensed matter
fascicolo: 14,
volume: 221,
anno: 1996,
pagine: 126  133
 SICI:
 09214526(1996)221:14<126:CMOTSR>2.0.ZU;2F
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 COMMENSURATEINCOMMENSURATE TRANSITION; BROMINEINTERCALATED GRAPHITE; SCANNING TUNNELING MICROSCOPY; ANISOTROPIC PHASETRANSITION; SYNCHROTRON XRAY; STATE POTTSMODEL; CLOCK MODEL; CORRELATION LENGTH; CRITICALBEHAVIOR; EXPONENTS;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Science Citation Index Expanded
 Citazioni:
 45
 Recensione:
 Indirizzi per estratti:



 Citazione:
 D.L. Abernathy et al., "CHIRAL MELTING OF THE SI(113)(3X1) RECONSTRUCTION", Physica. B, Condensed matter, 221(14), 1996, pp. 126133
Abstract
We report the results of synchrotron Xray scattering studies of the disordering of the Si(113) (3x1) reconstruction. A continuous commensuratesolid to incommensuratefluid transformation at Tc = 950 +/ 40 K is observed. At the transformation, the reconstructed layer becomes uniaxially incommensurate along the cubic (1(1) over bar0$)direction (xdirection). It remains commensurate along the (33(2) over bar)direction (ydirection). Critical scattering shows powerlaw behavior overnearly two decades of reduced temperature with exponents <(beta)over bar> = 0.66 +/ 0.05 for the incommensurability (epsilon), v(x) = 0.65+/ 0.07 for the inverse correlation length in the incommensurate direction (kappa(x)), v(y) = 1.06 +/ 0.07 for the inverse correlation length in the commensurate direction (kappa(y)), and y = 1.56 +/ 0.13 for the susceptibility (chi). Below Tc the variation of the square of the order parameter, proportional to the peak intensity at the commensurate position (I0), varies with an exponent 2 beta = 0.22 +/ 0.04. It is noteworthy that the correlation lengths in the disordered phase scale anisotropically, i.e. v(x)=v(y), and that the collected exponents do not conform to those of any previously measured universality class. Two universal constants of the transformation have also been measured. The ratio of the incommensurability and the inverse correlation length along the incommnensurate direction in the disordered phase is found to be independent of temperature, i.e. <(beta)over bar> = v(x), consistent with predictions for a new twodimensional chiral melting universality class, and to have the value w(0) = 1.6 +/ 0.2. Also, the hyperscaling ratio R(s) = chi kappa(x) kappa(y)/I0Vr, where Vr is the twodimensional resolution volume, is independent of the reduced temperature, consistent with the derived hyperscaling relationship v(x) + v(y) = y + 2 beta. According to the hypothesis of twoscalefactor universality, R(s) is a universal constant, which we find takes the value R(s) = 0.07 +/ 0.03. These results are discussed in the context of proposed phase diagrams of twodimensional threefolddegenerate uniaxialoverlayers where the chirality, or difference in free energy of lightand heavy domain walls, is varied. A comparison is made to recent LEED measurements of the (3 x 1)todisordered transformations of Si and Ge.
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Documento generato il 01/10/20 alle ore 14:40:21