Superstripes in the Low Energy Physics of Complex Quantum Matter at the Mesoscale

Abstract

A new low energy (in the range between 5 and 250 meV) physics focusing in the mesoscale (extending in the range between 1 nm and 100 μm) world is emerging. The intricate mesoscale world driven by quantum critical charge, orbital, and lattice fluctuations is now becoming the main topic of the Superstripes conference series.This field started in 1992 driven by the interest to understand the nanoscale phase separation of both "electronic matter" and "lattice matter" in cuprate perovskites [1], followed in 1996 by the series of Stripes conferences [2] and in 2008 by the present series of Superstripes conferences [3]. While the majority of the scientific community working in high temperature physics was accepting for 25 years the dogma of a uniform CuO 2 plane and a single electronic component, the small scientific community of the Stripes conferences proposed that an intrinsic nontrivial inhomogeneity, with different electronic components and anomalous local lattice fluctuations, was a key feature for the emergence of high temperature superconductivity [3][4][5][6]. The complex scenario object of discussions was characterized by a nanoscale phase separation with the competition of different phases in nanoscale domains: (i) short-range spin density wave SDW puddles,; ii) short-range incommensurate charge density wave CDW puddles, and (iii)A. Bianconi ( ) Rome International Center for Materials Science Superstripes, RICMASS, Via dei Sabelli 119/A, 00185, Rome, Italy e-mail: antonio.bianconi@ricmass.eu superconducting domains. This new scenario, called "superstripes" [7,8] is similar to emulsions in soft matter, where multiple phases at small length scales coexist. The superstripes scenario is today well supported by new experimental methods. The nanoscale phase separation takes place in the mesoscopic world intermediate between the atomic scale (for d less than 1 nm) and the macroscopic world (for d larger than 100 μm). All experiments show that the essential interactions are in the low energy range which is the same range as that of many body interactions determining the emergence of life in the cell.In materials science, the new low energy physics is determining advances in new nanotechnologies controlling the structure and textures in the mesoscopic scale.Several research groups have reported at Superstripes 2014 advances on charge density wave physics [9][10][11]. A new type of light, synchrotron radiation (SR), to investigate the mesoscale matter organization, became available worldwide only in this last 20 years. The invention of the synchrotron radiation source, the storage ring, was made in the 1960s, in Frascati by Bruno Touschek, and the first large synchrotron radiation facilities were developed at Stanford and Frascati in the 1970s. But it was only in these last 20 years that synchrotron radiation was available worldwide and it has allowed to image and control magnetic, lattice, and charge complexity in the mesoscale. The new methodologies probe multiscale spatial and temporal complexity in the low energy ...

Measuring the Electron–Phonon Interaction in Two-Dimensional Superconductors with He-Atom Scattering

“…Given the layered structure of these materials and the good quality of their surfaces, high-resolution HAS studies of their complex phonon structure and of mode-selected e-ph coupling constants would certainly help to further advance the understanding of high-T c superconductivity. The simultaneous information on dynamics and structure of the surface electron density that can be obtained with HAS would also be instrumental in investigating certain aspects of high-T c materials, e.g., phase separation [132], heterogeneity [133,134] and the superstripes landscape [135][136][137] made of multiscale puddles of CDWs from 3 nm to hundreds of nm [138] controlled by doping and elastic strain [139]. The nanoscale CDW texturing has been observed in 1T-TiSe 2 [140] where by Ti self-doping the Fermi level is tuned near a Lifshitz transition in correlated multi-band systems as was predicted theoretically [141].…”

Structure and Composition of the 200 K‐Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH−)(H3S+)

“…However, the Tc of the deuterated sample D2S is reduced to 90 K at the highest pressure corresponding to an isotope exponent α ≈ 1, and this exponent varies with pressure. [ 21 ] Recently, Bianconi and Jahlborg, [ 22 ] showed that these observations are not explained by the single gap superconductivity theory of Eliashberg [23] and Allen-Dynes, [24] and pointed out the need to consider a multigap superconductivity theory.In summary, concerning the high-Tc superconducting phase of H2S under high pressure, our work presents a picture different from the currently adopted one. Namely, H2S does not decompose into H3S and S, but dissociates under the formation of a perovskite type structure (SH -)(H3S + ).…”

“…However, the Tc of the deuterated sample D2S is reduced to 90 K at the highest pressure corresponding to an isotope exponent α ≈ 1, and this exponent varies with pressure. [ 21 ] Recently, Bianconi and Jahlborg, [ 22 ] showed that these observations are not explained by the single gap superconductivity theory of Eliashberg [23] and Allen-Dynes, [24] and pointed out the need to consider a multigap superconductivity theory.…”

From Quantum Paraelectric/Ferroelectric Perovskite Oxides to High Temperature Superconducting Copper Oxides -- In Honor of Professor K.A. Müller for His Lifework

“…Structurally, depending on the dopant atom M, carrier-doped tungsten oxides (M x WO 3 ) are classified into two different categories: perovskite or hexagonal. Both structures consist of WO 6 octahedra that form a corner-sharing network, though, in many cases, each octahedron exhibits a significant distortion [136][137][138]. Early on, it was discovered that these tungsten bronzes become superconductors when small amounts x of M are added.…”