Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

2013

Journal or Book Title

Journal of Physics: Condensed Matter

Volume

25

Issue

48

First Page

485002-1

Last Page

485002-9

DOI

10.1088/0953-8984/25/48/485002

Abstract

We have characterized the (010) surface of Gd5Ge4 using scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy. Data from different samples have the following features in common: (1) the surface composition equals the bulk composition to within 5 at.%, both after ion etching and after annealing at temperatures of 400–1200 K; and (2) the surface exhibits terraces of two types. The height of the steps between similar terraces corresponds well to the separation between equivalent layers along the h010i direction in the bulk structure. Density functional theory (DFT) shows that the surface energy of the (0001) plane of hexagonal close-packed Gd is lower than that of the (111) plane of diamond-type Ge, suggesting that surfaces of Gd5Ge4 (for comparable density) should be rich in Gd. Indeed, DFT shows that among the bulk terminations of Gd5Ge4, a pure Ge termination is not favored. Each of the three remaining terminations (two pure Gd and one mixed, Gd–Ge) has its minimum surface energy in a different range of the possible Gd chemical potentials, indicating that different terminations may be stable under different conditions. DFT shows that the heights of the steps between dissimilar terraces, measured in STM, are consistent with the two pure Gd terminations.

Comments

This is a manuscript of an article from Journal of Physics: Condensed Matter 25 (2013): 485002, doi: 10.1088/0953-8984/25/48/485002. Posted with permission.

Copyright Owner

IOP Publishing

Language

en

File Format

application/pdf

Published Version

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