Abstract
Ridged, orthorhombic two-dimensional atomic crystals with a bulk Pnma structure such as black phosphorus and monochalcogenide monolayers are an exciting and novel material platform for a host of applications. Key to their crystallinity, monolayers of these materials have a 4-fold degenerate structural ground state, and a single energy scale EC (representing the elastic energy required to switch the longer lattice vector along the x- or y-direction) determines how disordered these monolayers are at finite temperature. Disorder arises when nearest neighboring atoms become gently reassigned as the system is thermally excited beyond a critical temperature Tc that is proportional to EC/kB. EC is tunable by chemical composition and it leads to a classification of these materials into two categories: (i) Those for which EC ≥ kBTm, and (ii) those having kBTm > EC ≥ 0, where Tm is a given material's melting temperature. Black phosphorus and SiS monolayers belong to category (i): these materials do not display an intermediate order-disorder transition and melt directly. All other monochalcogenide monolayers with EC > 0 belonging to class (ii) will undergo a two-dimensional transition prior to melting. EC/kB is slightly larger than room temperature for GeS and GeSe, and smaller than 300 K for SnS and SnSe monolayers, so that these materials transition near room temperature. The onset of this generic atomistic phenomena is captured by a planar Potts model up to the order-disorder transition. The order-disorder phase transition in two dimensions described here is at the origin of the Cmcm phase being discussed within the context of bulk layered SnSe.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1704-1712 |
| Number of pages | 9 |
| Journal | Nano letters |
| Volume | 16 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 9 2016 |
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Keywords
- 2D atomic materials
- black phosphorus
- layered monochalcogenides
- molecular dynamics
- phase transitions
- structural degeneracies
ASJC Scopus subject areas
- Bioengineering
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering
Cite this
Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers. / Mehboudi, Mehrshad; Dorio, Alex M.; Zhu, Wenjuan; Van Der Zande, Arend; Churchill, Hugh O.H.; Pacheco-Sanjuan, Alejandro A.; Harriss, Edmund O.; Kumar, Pradeep; Barraza-Lopez, Salvador.
In: Nano letters, Vol. 16, No. 3, 09.03.2016, p. 1704-1712.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Two-Dimensional Disorder in Black Phosphorus and Monochalcogenide Monolayers
AU - Mehboudi, Mehrshad
AU - Dorio, Alex M.
AU - Zhu, Wenjuan
AU - Van Der Zande, Arend
AU - Churchill, Hugh O.H.
AU - Pacheco-Sanjuan, Alejandro A.
AU - Harriss, Edmund O.
AU - Kumar, Pradeep
AU - Barraza-Lopez, Salvador
PY - 2016/3/9
Y1 - 2016/3/9
N2 - Ridged, orthorhombic two-dimensional atomic crystals with a bulk Pnma structure such as black phosphorus and monochalcogenide monolayers are an exciting and novel material platform for a host of applications. Key to their crystallinity, monolayers of these materials have a 4-fold degenerate structural ground state, and a single energy scale EC (representing the elastic energy required to switch the longer lattice vector along the x- or y-direction) determines how disordered these monolayers are at finite temperature. Disorder arises when nearest neighboring atoms become gently reassigned as the system is thermally excited beyond a critical temperature Tc that is proportional to EC/kB. EC is tunable by chemical composition and it leads to a classification of these materials into two categories: (i) Those for which EC ≥ kBTm, and (ii) those having kBTm > EC ≥ 0, where Tm is a given material's melting temperature. Black phosphorus and SiS monolayers belong to category (i): these materials do not display an intermediate order-disorder transition and melt directly. All other monochalcogenide monolayers with EC > 0 belonging to class (ii) will undergo a two-dimensional transition prior to melting. EC/kB is slightly larger than room temperature for GeS and GeSe, and smaller than 300 K for SnS and SnSe monolayers, so that these materials transition near room temperature. The onset of this generic atomistic phenomena is captured by a planar Potts model up to the order-disorder transition. The order-disorder phase transition in two dimensions described here is at the origin of the Cmcm phase being discussed within the context of bulk layered SnSe.
AB - Ridged, orthorhombic two-dimensional atomic crystals with a bulk Pnma structure such as black phosphorus and monochalcogenide monolayers are an exciting and novel material platform for a host of applications. Key to their crystallinity, monolayers of these materials have a 4-fold degenerate structural ground state, and a single energy scale EC (representing the elastic energy required to switch the longer lattice vector along the x- or y-direction) determines how disordered these monolayers are at finite temperature. Disorder arises when nearest neighboring atoms become gently reassigned as the system is thermally excited beyond a critical temperature Tc that is proportional to EC/kB. EC is tunable by chemical composition and it leads to a classification of these materials into two categories: (i) Those for which EC ≥ kBTm, and (ii) those having kBTm > EC ≥ 0, where Tm is a given material's melting temperature. Black phosphorus and SiS monolayers belong to category (i): these materials do not display an intermediate order-disorder transition and melt directly. All other monochalcogenide monolayers with EC > 0 belonging to class (ii) will undergo a two-dimensional transition prior to melting. EC/kB is slightly larger than room temperature for GeS and GeSe, and smaller than 300 K for SnS and SnSe monolayers, so that these materials transition near room temperature. The onset of this generic atomistic phenomena is captured by a planar Potts model up to the order-disorder transition. The order-disorder phase transition in two dimensions described here is at the origin of the Cmcm phase being discussed within the context of bulk layered SnSe.
KW - 2D atomic materials
KW - black phosphorus
KW - layered monochalcogenides
KW - molecular dynamics
KW - phase transitions
KW - structural degeneracies
UR - http://www.scopus.com/inward/record.url?scp=84960533183&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84960533183&partnerID=8YFLogxK
U2 - 10.1021/acs.nanolett.5b04613
DO - 10.1021/acs.nanolett.5b04613
M3 - Article
C2 - 26866878
AN - SCOPUS:84960533183
VL - 16
SP - 1704
EP - 1712
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 3
ER -