@misc{MiaoFumagalliRossietal., author = {Miao, Hu and Fumagalli, Roberto and Rossi, M. and Lorenzana, Jos{\´e} and Seibold, G{\"o}tz and Yakhou-Harris, Flora and Kummer, K. and Brookes, Nicholas B. and Gu, G. D. and Braicovich, Lucio and Ghiringhelli, Giacomo Claudio and Dean, M. P. M.}, title = {Formation of Incommensurate Charge Density Waves in Cuprates}, series = {Physical Review X}, volume = {9}, journal = {Physical Review X}, number = {3}, issn = {2160-3308}, doi = {10.1103/PhysRevX.9.031042}, pages = {031042-1 -- 031042-11}, abstract = {Although charge density waves (CDWs) are omnipresent in cuprate high-temperature superconductors, they occur at significantly different wave vectors, confounding efforts to understand their formation mechanism. Here, we use resonant inelastic x-ray scattering to investigate the doping- and temperature-dependent CDW evolution in La₂₋ₓBaₓCuO₄ (x=0.115-0.155). We discover that the CDW develops in two stages with decreasing temperature. A precursor CDW with a quasicommensurate wave vector emerges first at high temperature. This doping-independent precursor CDW correlation originates from the CDW phase mode coupled with a phonon and "seeds" the low-temperature CDW with a strongly doping-dependent wave vector. Our observation reveals the precursor CDW and its phase mode as the building blocks of the highly intertwined electronic ground state in the cuprates.}, language = {en} } @misc{SeiboldArpaiaYingYingetal., author = {Seibold, G{\"o}tz and Arpaia, Riccardo and Ying Ying, Peng and Fumagalli, Roberto and Braicovich, Lucio and Di Castro, Carlo and Grilli, Marco and Ghiringhelli, Giacomo Claudio and Caprara, Sergio}, title = {Strange metal behaviour from charge density fluctuations in cuprates}, series = {Communications Physics}, volume = {4}, journal = {Communications Physics}, issn = {2399-3650}, doi = {10.1038/s42005-020-00505-z}, pages = {1 -- 6}, abstract = {Besides the mechanism responsible for high critical temperature superconductivity, the grand unresolved issue of the cuprates is the occurrence of a strange metallic state above the so-called pseudogap temperature T*. Even though such state has been successfully described within a phenomenological scheme, the so-called Marginal Fermi-Liquid theory, a microscopic explanation is still missing. However, recent resonant X-ray scattering experiments identified a new class of charge density fluctuations characterized by low characteristic energies and short correlation lengths, which are related to the well-known charge density waves. These fluctuations are present over a wide region of the temperature-vs-doping phase diagram and extend well above T*. Here we investigate the consequences of charge density fluctuations on the electron and transport properties and find that they can explain the strange metal phenomenology. Therefore, charge density fluctuations are likely the long-sought microscopic mechanism underlying the peculiarities of the metallic state of cuprates.}, language = {en} } @misc{MiaoLorenzanaSeiboldetal., author = {Miao, Hu and Lorenzana, Jos{\´e} and Seibold, G{\"o}tz and Peng, Yingying and Amorese, Andrea and Yakhou-Harris, Flora and Kummer, Kurt and Brookes, Nicholas B. and Konik, R. M. and Thampy, Vivek and Gu, G. D. and Ghiringhelli, Giacomo Claudio and Braicovich, Lucio and Dean, M. P. M.}, title = {High-temperature charge density wave correlations in La1.875Ba0.125CuO4 without spin-charge locking}, series = {Proceedings of the National Academy of Sciences of the United States of America PNAS}, volume = {114}, journal = {Proceedings of the National Academy of Sciences of the United States of America PNAS}, number = {47}, issn = {1091-6490}, doi = {10.1073/pnas.1708549114}, pages = {12430 -- 12435}, abstract = {Although all superconducting cuprates display charge-ordering tendencies, their low-temperature properties are distinct, impeding efforts to understand the phenomena within a single conceptual framework. While some systems exhibit stripes of charge and spin, with a locked periodicity, others host charge density waves (CDWs) without any obviously related spin order. Here we use resonant inelastic X-ray scattering to follow the evolution of charge correlations in the canonical stripe-ordered cuprate La1.875Ba0.125CuO4 across its ordering transition. We find that high-temperature charge correlations are unlocked from the wavevector of the spin correlations, signaling analogies to CDW phases in various other cuprates. This indicates that stripe order at low temperatures is stabilized by the coupling of otherwise independent charge and spin density waves, with important implications for the relation between charge and spin correlations in the cuprates.}, language = {en} } @misc{WahlbergArpaiaSeiboldetal., author = {Wahlberg, Eric and Arpaia, Riccardo and Seibold, G{\"o}tz and Rossi, Matteo and Fumagalli, Roberto and Trabaldo, Edoardo and Brookes, Nicholas B. and Braicovich, Lucio and Caprara, Sergio and Lombardi, Floriana and Gran, Ulf and Ghiringhelli, Giacomo Claudio and Bauch, Thilo}, title = {Restored strange metal phase through suppression of charge density waves in underdoped YBa2Cu3O7-δ}, series = {Science}, volume = {373}, journal = {Science}, number = {6562}, doi = {10.1126/science.abc8372}, pages = {1506 -- 1510}, abstract = {The normal state of optimally doped cuprates is dominated by the "strange metal" phase that shows a linear temperature (T) dependence of the resistivity persisting down to the lowest T. For underdoped cuprates, this behavior is lost below the pseudogap temperature T*, where charge density waves (CDWs), together with other intertwined local orders, characterize the ground state. We found that the T-linear resistivity of highly strained, ultrathin, underdoped YBa2Cu3O7-δ films is restored when the CDW amplitude, detected by resonant inelastic x-ray scattering, is suppressed. This observation suggests an intimate connection between the onset of CDWs and the departure from T-linear resistivity in underdoped cuprates. Our results illustrate the potential of using strain control to manipulate the ground state of quantum materials.}, language = {en} }