Elena Gati

Breakdown of Hooke’s law of elasticity at the Mott critical endpoint in an organic conductor

The coupling of the critical electronic system to a compressible lattice is found to drastically alter the Mott criticality. The Mott metal-insulator transition, a paradigm of strong electron-electron correlations, has been considered as a source of intriguing phenomena. Despite its importance for a wide range of materials, fundamental aspects of the transition, such as its universal properties, are still under debate. We report detailed measurements of relative length changes ΔL/L as a function of continuously controlled helium-gas pressure P for the organic conductor κ-(BEDT-TTF)2Cu[N(CN)2]Cl across the pressure-induced Mott transition. We observe strongly nonlinear variations of ΔL/L with pressure around the Mott critical endpoint, highlighting a breakdown of Hooke’s law of elasticity. We assign these nonlinear strain-stress relations to an intimate, nonperturbative coupling of the critical electronic system to the lattice degrees of freedom. Our results are fully consistent with mean-field criticality, predicted for electrons in a compressible lattice with finite shear moduli. We argue that the Mott transition for all systems that are amenable to pressure tuning shows the universal properties of an isostructural solid-solid transition.

Barlowite as a canted antiferromagnet: Theory and experiment

We investigate the structural, electronic and magnetic properties of the newly synthesized mineral barlowite Cu4(OH)6FBr which contains Cu2+ ions in a perfect kagome arrangement. In contrast to the spin-liquid candidate herbertsmithite ZnCu3(OH)6Cl2, kagome layers in barlowite are perfectly aligned due to the different bonding environments adopted by F- and Br- compared to Cl-. We perform density functional theory calculations to obtain the Heisenberg Hamiltonian parameters of Cu4(OH)6FBr which has a Cu2+ site coupling the kagome layers. The 3D network of exchange couplings together with a substantial Dzyaloshinskii-Moriya coupling lead to canted antiferromagnetic ordering of this compound at TN=15 K as observed by magnetic susceptibility measurements on single crystals.

Synthesis, Crystal Structure, Transport, and Magnetic Properties of Novel Ternary Copper Phosphides, A2Cu6P5 (A = Sr, Eu) and EuCu4P3

Three new ternary copper phosphides, Sr(2)Cu(6)P(5), Eu(2)Cu(6)P(5), and EuCu(4)P(3), have been synthesized from the elements in evacuated silica capsules. Eu(2)Cu(6)P(5) and Sr(2)Cu(6)P(5) adopt the Ca(2)Cu(6)P(5)-type structure, while EuCu(4)P(3) is isostructural to BaMg(4)Si(3) and still remains the only representative of this structure type among the ternary Cu pnictides. All three materials show metallic conductivity in the temperature range 2 K ≤ T ≤ 290 K, with no indication for superconductivity. For Eu(2)Cu(6)P(5) and EuCu(4)P(3), long-range magnetic order was observed, governed by 4f local moments on the Eu atoms with predominant ferromagnetic interactions. While Eu(2)Cu(6)P(5) shows a single ferromagnetic transition at T(C) = 34 K, the magnetic behavior of EuCu(4)P(3) is more complex, giving rise to three consecutive magnetic phase transitions at 70, 43, and 18 K.

Hydrostatic-pressure tuning of magnetic, nonmagnetic, and superconducting states in annealed Ca(Fe1−xCox)2As2

We report on measurements of the magnetic susceptibility and electrical resistance under He-gas pressure on single crystals of Ca(Fe

Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3

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Effects of Disorder on the Pressure-Induced Mott Transition in κ-(BEDT-TTF)2Cu[N(CN)2]Cl

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Combined effects of Sr substitution and pressure on the ground states in CaFe2As2

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Dilatometric Studies on Single Crystalline Barlowite – A Structurally Perfect Spin-1/2 Kagome System☆

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Evidence for Electronically Driven Ferroelectricity in a Strongly Correlated Dimerized BEDT-TTF Molecular Conductor

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Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ−(BEDT−TTF)2Hg(SCN)2Cl

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