Critical vacancy density for melting in two-dimensions: The case of high density Bi on Cu(111)

Raoul Van Gastel, Arie Van Houselt, Daniel Kaminski, Elias Vlieg, Harold J.W. Zandvliet, Bene Poelsema (Corresponding Author)

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Abstract

The two-dimensional melting/solidification transition of the high density [2012] phase of Bi on Cu(111) has been studied by means of low energy electron microscopy (LEEM). This well defined phase has an ideal concentration of one Bi atom per two Cu surface atoms (θ Bi = 0.500). The Bi density is determined accurately in situ and the highest melting temperature of 538 K occurs at exactly θ Bi = 0.500. A significantly reduced melting temperature is observed for lower Bi densities (θ Bi < 0.500) and, surprisingly, also for θ Bi > 0.500. At |Δ θ Bi| = 0.015 the melting temperature is reduced by about 20 K. This lowering of the melting temperature is attributed to a critical vacancy density at melting and we propose that this quantity triggers the 2D solid-liquid phase transition. For this particular system, the critical vacancy fraction for melting amounts to 5%-6%. Above θ Bi = 0.500 and near melting a homogeneous, unilaterally compressed phase, '[2012]' is observed, with a density that increases continuously with coverage. It is commensurate along and incommensurate along The ability to distinguish between Bi accommodated within the '[2012]' phase and Bi residing on top as a lattice gas by applying LEEM is of crucial importance for the analysis.

Original languageEnglish
Article number083045
JournalNew journal of physics
Volume20
Issue number8
DOIs
Publication statusPublished - 31 Aug 2018

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melting
electron microscopy
temperature
solidification
atoms
liquid phases
actuators
energy
gases

Keywords

  • 2D melting
  • Bi/Cu(111)
  • Low energy electron microscopy (LEEM)
  • Phase diagram

Cite this

@article{aa06e8769db545aca25910fbf6ae4af4,
title = "Critical vacancy density for melting in two-dimensions: The case of high density Bi on Cu(111)",
abstract = "The two-dimensional melting/solidification transition of the high density [2012] phase of Bi on Cu(111) has been studied by means of low energy electron microscopy (LEEM). This well defined phase has an ideal concentration of one Bi atom per two Cu surface atoms (θ Bi = 0.500). The Bi density is determined accurately in situ and the highest melting temperature of 538 K occurs at exactly θ Bi = 0.500. A significantly reduced melting temperature is observed for lower Bi densities (θ Bi < 0.500) and, surprisingly, also for θ Bi > 0.500. At |Δ θ Bi| = 0.015 the melting temperature is reduced by about 20 K. This lowering of the melting temperature is attributed to a critical vacancy density at melting and we propose that this quantity triggers the 2D solid-liquid phase transition. For this particular system, the critical vacancy fraction for melting amounts to 5{\%}-6{\%}. Above θ Bi = 0.500 and near melting a homogeneous, unilaterally compressed phase, '[2012]' is observed, with a density that increases continuously with coverage. It is commensurate along and incommensurate along The ability to distinguish between Bi accommodated within the '[2012]' phase and Bi residing on top as a lattice gas by applying LEEM is of crucial importance for the analysis.",
keywords = "2D melting, Bi/Cu(111), Low energy electron microscopy (LEEM), Phase diagram",
author = "{Van Gastel}, Raoul and {Van Houselt}, Arie and Daniel Kaminski and Elias Vlieg and Zandvliet, {Harold J.W.} and Bene Poelsema",
year = "2018",
month = "8",
day = "31",
doi = "10.1088/1367-2630/aada52",
language = "English",
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journal = "New journal of physics",
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number = "8",

}

Critical vacancy density for melting in two-dimensions : The case of high density Bi on Cu(111). / Van Gastel, Raoul; Van Houselt, Arie; Kaminski, Daniel; Vlieg, Elias; Zandvliet, Harold J.W.; Poelsema, Bene (Corresponding Author).

In: New journal of physics, Vol. 20, No. 8, 083045, 31.08.2018.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Critical vacancy density for melting in two-dimensions

T2 - The case of high density Bi on Cu(111)

AU - Van Gastel, Raoul

AU - Van Houselt, Arie

AU - Kaminski, Daniel

AU - Vlieg, Elias

AU - Zandvliet, Harold J.W.

AU - Poelsema, Bene

PY - 2018/8/31

Y1 - 2018/8/31

N2 - The two-dimensional melting/solidification transition of the high density [2012] phase of Bi on Cu(111) has been studied by means of low energy electron microscopy (LEEM). This well defined phase has an ideal concentration of one Bi atom per two Cu surface atoms (θ Bi = 0.500). The Bi density is determined accurately in situ and the highest melting temperature of 538 K occurs at exactly θ Bi = 0.500. A significantly reduced melting temperature is observed for lower Bi densities (θ Bi < 0.500) and, surprisingly, also for θ Bi > 0.500. At |Δ θ Bi| = 0.015 the melting temperature is reduced by about 20 K. This lowering of the melting temperature is attributed to a critical vacancy density at melting and we propose that this quantity triggers the 2D solid-liquid phase transition. For this particular system, the critical vacancy fraction for melting amounts to 5%-6%. Above θ Bi = 0.500 and near melting a homogeneous, unilaterally compressed phase, '[2012]' is observed, with a density that increases continuously with coverage. It is commensurate along and incommensurate along The ability to distinguish between Bi accommodated within the '[2012]' phase and Bi residing on top as a lattice gas by applying LEEM is of crucial importance for the analysis.

AB - The two-dimensional melting/solidification transition of the high density [2012] phase of Bi on Cu(111) has been studied by means of low energy electron microscopy (LEEM). This well defined phase has an ideal concentration of one Bi atom per two Cu surface atoms (θ Bi = 0.500). The Bi density is determined accurately in situ and the highest melting temperature of 538 K occurs at exactly θ Bi = 0.500. A significantly reduced melting temperature is observed for lower Bi densities (θ Bi < 0.500) and, surprisingly, also for θ Bi > 0.500. At |Δ θ Bi| = 0.015 the melting temperature is reduced by about 20 K. This lowering of the melting temperature is attributed to a critical vacancy density at melting and we propose that this quantity triggers the 2D solid-liquid phase transition. For this particular system, the critical vacancy fraction for melting amounts to 5%-6%. Above θ Bi = 0.500 and near melting a homogeneous, unilaterally compressed phase, '[2012]' is observed, with a density that increases continuously with coverage. It is commensurate along and incommensurate along The ability to distinguish between Bi accommodated within the '[2012]' phase and Bi residing on top as a lattice gas by applying LEEM is of crucial importance for the analysis.

KW - 2D melting

KW - Bi/Cu(111)

KW - Low energy electron microscopy (LEEM)

KW - Phase diagram

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