We investigated the structural transformations of the hexagonal phase of Ge2Sb2Te5 under pressure by means of ab initio molecular dynamics with a variable simulation cell. To overcome the enthalpy barriers between the different phases we used metadynamics techniques. We reproduced the hexagonal-to-bcc transformation under pressure found experimentally. The bcc phase retains a partial chemical order, as opposed to a second bcc phase we generated by pressuring the amorphous phase. This structural difference is suggested to be responsible for the memory effect uncovered experimentally, the bcc phase reverting to the amorphous or to the hexagonal phase upon decompression, depending on the type of precursor phase it originates from.

Caravati, S., Sosso, G., Bernasconi, M., Parrinello, M. (2013). Density functional simulations of hexagonal Ge_{2}Sb_{2}Te_{5} at high pressure. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 87(9), 094117-094128 [10.1103/PhysRevB.87.094117].

Density functional simulations of hexagonal Ge_{2}Sb_{2}Te_{5} at high pressure

CARAVATI, SEBASTIANO;SOSSO, GABRIELE CESARE;BERNASCONI, MARCO;
2013

Abstract

We investigated the structural transformations of the hexagonal phase of Ge2Sb2Te5 under pressure by means of ab initio molecular dynamics with a variable simulation cell. To overcome the enthalpy barriers between the different phases we used metadynamics techniques. We reproduced the hexagonal-to-bcc transformation under pressure found experimentally. The bcc phase retains a partial chemical order, as opposed to a second bcc phase we generated by pressuring the amorphous phase. This structural difference is suggested to be responsible for the memory effect uncovered experimentally, the bcc phase reverting to the amorphous or to the hexagonal phase upon decompression, depending on the type of precursor phase it originates from.
Articolo in rivista - Articolo scientifico
ab-initio simulations, phase transitions, high pressure, phase change materials
English
2013
87
9
094117
094128
none
Caravati, S., Sosso, G., Bernasconi, M., Parrinello, M. (2013). Density functional simulations of hexagonal Ge_{2}Sb_{2}Te_{5} at high pressure. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 87(9), 094117-094128 [10.1103/PhysRevB.87.094117].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/45077
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