TY - JOUR

T1 - The processes of ordering and formation of two-dimensional glasses at metal surfaces

AU - Fedorus, A. G.

AU - Mitryaev, A. A.

AU - Mukhtarov, M. A.

AU - Pfnür, Herbert

AU - Vedula, Yu S.

AU - Naumovets, A. G.

N1 - Funding information: We thank V.V. Maslov for helpful discussion. This work was supported by National Academy of Sciences of Ukraine (Project VTs-92) and by the Basic Research Foundation of the Ministry of Ukraine for Education and Science (Project 02.07/00047). Support by the Deutsche Forschungsgemeinschaft is also gratefully acknowledged.

PY - 2006/2/3

Y1 - 2006/2/3

N2 - Using the experimental results obtained for the Dy-Mo(1 1 2) system, we discuss the possibilities and mechanisms of formation of two-dimensional (2D) glasses on metal surfaces. It has been found that in the coverage range 0.07 < θ < 0.58, ordered Dy superstructures formed and observed at T < 400 K are irreversibly destroyed by annealing to higher temperatures and turn into an amorphous (glass) structure on cooling. It is supposed that this conversion is caused by the formation, at T > 400 K, of a Dy-Mo surface alloy in which the rate of Dy surface diffusion is strongly reduced in comparison with its value in the absence of alloying. As a result, the mobility of Dy adatoms becomes too low at the temperatures corresponding to the ordered equilibrium state of the surface, and this state cannot be achieved in reasonable relaxation time. This interpretation is corroborated by the experimental data on substantial suppression of surface diffusion in some coadsorbed layers. Since surface glasses contact with ordered (crystalline) substrates, their structure may have a peculiar character different from that of "conventional" metal glasses. Surface glasses can find a number of applications as rather stable systems that combine low dimensionality, specific electronic structure of their constituents and extremely high density of defects.

AB - Using the experimental results obtained for the Dy-Mo(1 1 2) system, we discuss the possibilities and mechanisms of formation of two-dimensional (2D) glasses on metal surfaces. It has been found that in the coverage range 0.07 < θ < 0.58, ordered Dy superstructures formed and observed at T < 400 K are irreversibly destroyed by annealing to higher temperatures and turn into an amorphous (glass) structure on cooling. It is supposed that this conversion is caused by the formation, at T > 400 K, of a Dy-Mo surface alloy in which the rate of Dy surface diffusion is strongly reduced in comparison with its value in the absence of alloying. As a result, the mobility of Dy adatoms becomes too low at the temperatures corresponding to the ordered equilibrium state of the surface, and this state cannot be achieved in reasonable relaxation time. This interpretation is corroborated by the experimental data on substantial suppression of surface diffusion in some coadsorbed layers. Since surface glasses contact with ordered (crystalline) substrates, their structure may have a peculiar character different from that of "conventional" metal glasses. Surface glasses can find a number of applications as rather stable systems that combine low dimensionality, specific electronic structure of their constituents and extremely high density of defects.

KW - Adsorbate structure

KW - Glass surfaces

KW - Glass transitions

KW - Kinetics of annealing

KW - LEED

KW - Surface diffusion

KW - Surface phase transitions

KW - Surface structure

KW - Work function measurements

UR - http://www.scopus.com/inward/record.url?scp=33646412851&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2005.11.040

DO - 10.1016/j.susc.2005.11.040

M3 - Article

AN - SCOPUS:33646412851

VL - 600

SP - 1566

EP - 1573

JO - Surface Science

JF - Surface Science

SN - 0039-6028

IS - 8

ER -