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Rousseau, Roger; Boero, Mauro; Bernasconi, Marco; Parrinello, Michele; Terakura, Kiyoyuki

doi:10.1103/physrevlett.85.1254

Cited by 51 publications

(41 citation statements)

References 27 publications

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“…Indeed, the values of the total energy for the F state approach those of the AF state, until a transition in the magnetic state arises 22 at values of the order of 7 GPa, as shown above when describing the content of Table 1 and Figure 2. This is consistent with the available experimental outcome 23 and supports the notion of a pressure-controlled spin-switch mechanism. The only warning we have to put forward is the larger value of the theoretical pressure at which such a transition occurs with respect to the experimental one (about 1.5 GPa).…”

Section: ■ Results and Discussionsupporting

confidence: 92%

Tuning Magnetic Properties with Pressure in Hybrid Organic–Inorganic Materials: The Case of Copper Hydroxide Acetate

2014

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The magnetic response and related spin topology of the hybrid organic−inorganic material copper hydroxide acetate Cu 2 (OH) 3 (CH 3 COO)·H 2 O are studied as a function of an applied external pressure within first-principles approaches. We show that structural changes induced by high pressure affect the Cu−O−Cu angles, particularly when the bridging O atom belongs to the CH 3 COO chains, with a sharp transition occurring above 2.75 GPa. These geometrical modifications are responsible for a transition from an antiferromagnetic (at the ambient pressure ground state) to a ferromagnetic state at high pressure (∼7 GPa). Our results are in agreement with the experimental outcome. They provide a guideline for applications of these composite systems in nanoelectronics and disclose new frontiers in the design of memory devices based on this family of hybrid lamellar materials. ■ INTRODUCTIONIn organic−inorganic lamellar hybrid materials, a wide variety of organic chains can be inserted within the host architecture, i.e., between the transition metal ion-based oxide layers. This allows for a fine-tuning of the physical and chemical properties of the resulting system, mainly because of the flexibility and the chemical nature of the organic chains. The use of an external macroscopic quantity, such as pressure, is a practical tool to tune the properties of these materials and, ultimately, control their magnetic character. 1 This is a promising path toward applications in next-generation nanoelectronics, especially memory switches and data storage devices. 2 A representative prototype of these lamellar organic−inorganic materials is copper hydroxide acetate, Cu 2 (OH) 3 (CH 3 COO)·H 2 O. Such a compound consists of triangular arrays of Cu II hydroxide building blocks forming a two-dimensional host structure able to accommodate an organic moiety, specifically CH 3 COO − spacers. 3,4 The distance between two adjacent Cu hydroxide layers depends on the chemical nature and the conformation of the inserted organic chains. 2 If an external pressure is applied along the crystallographic direction orthogonal to the Cu hydroxide planes, structural changes occur in the organic chains as a response to the reduction of the interlayer distance. Eventually, increasing values of the pressure are able to modify the magnetic properties of the material. In former studies, 2 a comparison of the magnetic behavior of Cu 2 (NO 3 )(OH) 3 and Cu 2 (OH) 3 (CH 3 COO)·H 2 O has shown for both an antiferromagnetic (AF) character as a ground state. However, the replacement of NO 3 − with the longer CH 3 COO − acetate units has the net effect of promoting the arising of a weak ferromagnetic (F) intralayer character, as opposed to the persisting AF character of Cu 2 (NO 3 )(OH) 3 .In our previous investigations, 3,4 first-principles approaches 5,6 based on the density functional theory 7 (DFT) have been useful to complement the missing structural information concerning the position of atoms, escaping experimental probes, and to provide insight into the bond...

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Section: ■ Results and Discussionsupporting

confidence: 92%

Tuning Magnetic Properties with Pressure in Hybrid Organic–Inorganic Materials: The Case of Copper Hydroxide Acetate

2014

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“…The pressure-induced formation of ionic solid on molecular systems has been predicted theoretically for NH 3 20 , similar to that in liquid water [12][13][14]23 . .…”

Section: Discussionmentioning

confidence: 77%

High pressure partially ionic phase of water ice

et al. 2011

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Water ice dissociates into a superionic solid at high temperature ( > 2,000 K) and pressure, where oxygen forms the lattice, but hydrogen diffuses completely. At low temperature, however, the dissociation into an ionic ice of hydronium (H 3 o) + hydroxide (oH) − is not expected because of the extremely high energy cost (~1.5 eV) of proton transfer between H 2 o molecules. Here we show the pressure-induced formation of a partially ionic phase (monoclinic P2 1 structure) consisting of coupled alternate layers of (oH) δ − and (H 3 o) δ + (δ = 0.62) in water ice predicted by particle-swarm optimization structural search at zero temperature and pressures of > 14 mbar. The occurrence of this ionic phase follows the break-up of the typical o-H covalently bonded tetrahedrons in the hydrogen symmetric atomic phases and is originated from the volume reduction favourable for a denser structure packing.

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“…In the same study Li et al 15 also showed that pressure-induced decomposition of H 2 S into its elements was thermodynamically unfavorable. This result overturned the conclusion from a DFT study 28 that pressure-induced decomposition into the elements might occur, and suggested that new H/S compounds could be formed.…”

Section: Introductionmentioning

confidence: 41%

Perspective: Role of structure prediction in materials discovery and design

Needs¹,

Pickard

2016

APL Materials

124

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Materials informatics owes much to bioinformatics and the Materials Genome Initiative has been inspired by the Human Genome Project. But there is more to bioinformatics than genomes, and the same is true for materials informatics. Here we describe the rapidly expanding role of searching for structures of materials using first-principles electronic-structure methods. Structure searching has played an important part in unraveling structures of dense hydrogen and in identifying the record-high-temperature superconducting component in hydrogen sulfide at high pressures. We suggest that first-principles structure searching has already demonstrated its ability to determine structures of a wide range of materials and that it will play a central and increasing part in materials discovery and design.

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Ab initioSimulation of Phase Transitions and Dissociation ofH2Sat High Pressure

Cited by 51 publications

References 27 publications

Tuning Magnetic Properties with Pressure in Hybrid Organic–Inorganic Materials: The Case of Copper Hydroxide Acetate

Tuning Magnetic Properties with Pressure in Hybrid Organic–Inorganic Materials: The Case of Copper Hydroxide Acetate

High pressure partially ionic phase of water ice

Perspective: Role of structure prediction in materials discovery and design

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