A quasi-1D system is prepared using the Pt(110) surface as a template. The electronic surface resonance structure is studied by angle-resolved photoemission spectroscopy for the clean surface as well as for different Bromine coverages. A Fermi surface mapping reveals saddle points at the Fermi level in the interior of the surface Brillouin zone. Correspondingly, a maximum in the static response function chi(q, 0) at the connecting vector q is expected. With 1/2G(x) < q < 2/3G(x) one observes indeed a 3-fold periodicity around defects and a 2-fold periodicity at low temperature for I similar to(Br) = 0.5 ML. Cooling of a defect-free c(2x2)-Br/Pt(110) preparation counter-intuitively results in a loss of long-range order. Motivated by DFT calculations this is attributed to an anomalous order-order phase transition into the (2x1) phase accompanied by intense, strongly anisotropic fluctuations within a temperature range of similar to 200 K. The peculiar behaviour is rationalised in terms of a competition between inter-adsorbate repulsion and an adsorbate triggered 2k(F) interaction in the substrate.
Amann P, Cordin M, Braun C, Lechner BAJ, Menzel A, Bertel E, et al. (2010). Electronically driven phase transitions in a quasi-one-dimensional adsorbate system. THE EUROPEAN PHYSICAL JOURNAL. B, CONDENSED MATTER PHYSICS, 75(1), 15-22 [10.1140/epjb/e2010-00026-5].
Electronically driven phase transitions in a quasi-one-dimensional adsorbate system
FRANCHINI, CESAREMembro del Collaboration Group
;
2010
Abstract
A quasi-1D system is prepared using the Pt(110) surface as a template. The electronic surface resonance structure is studied by angle-resolved photoemission spectroscopy for the clean surface as well as for different Bromine coverages. A Fermi surface mapping reveals saddle points at the Fermi level in the interior of the surface Brillouin zone. Correspondingly, a maximum in the static response function chi(q, 0) at the connecting vector q is expected. With 1/2G(x) < q < 2/3G(x) one observes indeed a 3-fold periodicity around defects and a 2-fold periodicity at low temperature for I similar to(Br) = 0.5 ML. Cooling of a defect-free c(2x2)-Br/Pt(110) preparation counter-intuitively results in a loss of long-range order. Motivated by DFT calculations this is attributed to an anomalous order-order phase transition into the (2x1) phase accompanied by intense, strongly anisotropic fluctuations within a temperature range of similar to 200 K. The peculiar behaviour is rationalised in terms of a competition between inter-adsorbate repulsion and an adsorbate triggered 2k(F) interaction in the substrate.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
