@misc{SeiboldCapraraGrillietal., author = {Seibold, G{\"o}tz and Caprara, Sergio and Grilli, Marco and Raimondi, Roberto}, title = {Theory of the Spin Galvanic Effect at Oxide Interfaces}, series = {Physical Review Letters}, volume = {119}, journal = {Physical Review Letters}, number = {25}, issn = {1092-0145}, doi = {10.1103/PhysRevLett.119.256801}, abstract = {The spin galvanic effect (SGE) describes the conversion of a nonequilibrium spin polarization into a transverse charge current. Recent experiments have demonstrated a large conversion efficiency for the two-dimensional electron gas formed at the interface between two insulating oxides, LaAlO3 and SrTiO3. Here, we analyze the SGE for oxide interfaces within a three-band model for the Ti t2g orbitals which displays an interesting variety of effective spin-orbit couplings in the individual bands that contribute differently to the spin-charge conversion. Our analytical approach is supplemented by a numerical treatment where we also investigate the influence of disorder and temperature, which turns out to be crucial to providing an appropriate description of the experimental data.}, language = {en} } @misc{SeiboldCapraraGrillietal., author = {Seibold, G{\"o}tz and Caprara, Sergio and Grilli, Marco and Raimondi, Roberto}, title = {Intrinsic spin Hall effect in systems with striped spin-orbit coupling}, series = {epl : a letters journal exploring the frontiers of physics}, volume = {112}, journal = {epl : a letters journal exploring the frontiers of physics}, number = {1}, issn = {1286-4854}, doi = {http://dx.doi.org/10.1209/0295-5075/112/17004}, pages = {17004-p1 -- 17004-p6}, language = {en} } @inproceedings{SeiboldCapraraRaimondi, author = {Seibold, G{\"o}tz and Caprara, Sergio and Raimondi, Roberto}, title = {Theory of charge-spin conversion at oxide interfaces: the inverse spin-galvanic effect}, series = {Spintronics XI, SPIE Nanoscience + Engineering, 19-23 August 2018, San Diego, California, United States}, booktitle = {Spintronics XI, SPIE Nanoscience + Engineering, 19-23 August 2018, San Diego, California, United States}, editor = {Drouhin, Henri-Jean and Wegrowe, Jean-Eric and Razeghi, Manijeh and Jaffr{\`e}s, Henri}, publisher = {Spie}, address = {Bellingham, USA}, doi = {10.1117/12.2319592}, abstract = {We evaluate the non-equilibrium spin polarization induced by an applied electric field for a tight-binding model of electron states at oxides interfaces in LAO/STO heterostructures. By a combination of analytic and numerical approaches we investigate how the spin texture of the electron eigenstates due to the interplay of spin-orbit coupling and inversion asymmetry determines the sign of the induced spin polarization as a function of the chemical potential or band filling, both in the absence and presence of local disorder. With the latter, we find that the induced spin polarization evolves from a non monotonous behavior at zero temperature to a monotonous one at higher temperature. Our results may provide a sound framework for the interpretation of recent experiments.}, language = {en} } @misc{BovenziFinocchiaroScopignoetal., author = {Bovenzi, Nicolo and Finocchiaro, Francesca and Scopigno, Nicantro and Bucheli, Daniel and Caprara, Sergio and Seibold, G{\"o}tz and Grilli, Marco}, title = {Possible Mechanisms of Electronic Phase Separation in Oxide Interfaces}, series = {Journal of Superconductivity and Novel Magnetism}, volume = {28}, journal = {Journal of Superconductivity and Novel Magnetism}, number = {4}, issn = {1557-1939}, doi = {10.1007/s10948-014-2903-7}, pages = {1273 -- 1277}, abstract = {LaAlO 3/SrTiO 3 and LaTiO 3/SrTiO 3 (LXO / STO) interfaces are known to host a strongly inhomogeneous (nearly) two-dimensional electron gas (2DEG). In this work, we present three unconventional electronic mechanisms of electronic phase separation (EPS) in a 2DEG as a possible source of inhomogeneity in oxide interfaces. Common to all three mechanisms is the dependence of some (interaction) potential on the 2DEGs density. We first consider a mechanism resulting from a sizable density-dependent Rashba spin-orbit coupling. Next, we point out that an EPS may also occur in the case of a density-dependent superconducting pairing interaction. Finally, we show that the confinement of the 2DEG to the interface by a density-dependent, self-consistent electrostatic potential can by itself cause an EPS.}, language = {en} } @misc{CapraraDiCastroMirarchietal., author = {Caprara, Sergio and Di Castro, Carlo and Mirarchi, Giovanni and Seibold, G{\"o}tz and Grilli, Marco}, title = {Dissipation-driven strange metal behavior}, series = {Communications Physics}, journal = {Communications Physics}, number = {5}, issn = {2399-3650}, doi = {10.1038/s42005-021-00786-y}, pages = {1 -- 7}, abstract = {Anomalous metallic properties are often observed in the proximity of quantum critical points, with violation of the Fermi Liquid paradigm. We propose a scenario where, near the quantum critical point, dynamical fluctuations of the order parameter with finite correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface. This scattering produces a strange metallic behavior, which is extended to the lowest temperatures by an increase of the damping of the fluctuations. We phenomenologically identify one single parameter ruling this increasing damping when the temperature decreases, accounting for both the linear-in-temperature resistivity and the seemingly divergent specific heat observed, e.g., in high-temperature superconducting cuprates and some heavy-fermion metals.}, 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{MirarchiSeiboldDiCastroetal., author = {Mirarchi, Giovanni and Seibold, G{\"o}tz and Di Castro, Carlo and Grilli, Marco and Caprara, Sergio}, title = {The Strange-Metal Behavior of Cuprates}, series = {Condensed Matter}, volume = {7}, journal = {Condensed Matter}, number = {1}, issn = {2410-3896}, doi = {10.3390/condmat7010029}, pages = {1 -- 17}, abstract = {Recent resonant X-ray scattering experiments on cuprates allowed to identify a new kind of collective excitations, known as charge density fluctuations, which have finite characteristic wave vector, short correlation length and small characteristic energy. It was then shown that these fluctuations provide a microscopic scattering mechanism that accounts for the anomalous transport properties of cuprates in the so-called strange-metal phase and are a source of anomalies in the specific heat. In this work, we retrace the main steps that led us to attributing a central role to charge density fluctuations in the strange-metal phase of cuprates, discuss the state of the art on the issue and provide an in-depth analysis of the contribution of charge density fluctuations to the specific heat.}, language = {en} } @misc{CapatiCapraraDiCastroetal., author = {Capati, Matteo and Caprara, Sergio and Di Castro, Carlo and Grilli, Marco and Seibold, G{\"o}tz and Lorenzana, Jos{\´e}}, title = {Electronic polymers and soft-matter-like broken symmetries in underdoped cuprates}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, issn = {2041-1723}, doi = {doi:10.1038/ncomms8691}, pages = {7691}, abstract = {Empirical evidence in heavy fermion, pnictide and other systems suggests that unconventional superconductivity appears associated to some form of real-space electronic order. For the cuprates, despite several proposals, the emergence of order in the phase diagram between the commensurate antiferromagnetic state and the superconducting state is not well understood. Here we show that in this regime doped holes assemble in 'electronic polymers'. Within a Monte Carlo study, we find that in clean systems by lowering the temperature the polymer melt condenses first in a smectic state and then in a Wigner crystal both with the addition of inversion symmetry breaking. Disorder blurs the positional order leaving a robust inversion symmetry breaking and a nematic order, accompanied by vector chiral spin order and with the persistence of a thermodynamic transition. Such electronic phases, whose properties are reminiscent of soft-matter physics, produce charge and spin responses in good accord with experiments.}, language = {en} } @misc{CapraraGrilliDiCastroetal., author = {Caprara, Sergio and Grilli, Marco and Di Castro, Carlo and Seibold, G{\"o}tz}, title = {Pseudogap and (An)isotropic Scattering in the Fluctuating Charge-Density Wave Phase of Cuprates}, series = {Journal of Superconductivity and Novel Magnetism}, volume = {30}, journal = {Journal of Superconductivity and Novel Magnetism}, number = {1}, issn = {1557-1939}, doi = {10.1007/s10948-016-3775-9}, pages = {25 -- 30}, abstract = {We present a general scenario for high-temperature superconducting cuprates, based on the presence of dynamical charge density waves (CDWs) and to the occurrence of a CDW quantum critical point, which occurs, e.g., at doping p ≈ 0.16 in YBa2Cu3O6 + δ (YBCO). In this framework, the pseudogap temperature T∗ is interpreted in terms of a reduction of the density of states due to incipient CDW and, at lower temperature to the possible formation of incoherent superconducting pairs. The dynamically fluctuating character of CDW accounts for the different temperatures at which the CDW onset revealed by X-ray scattering (Tons(p)), and the static three-dimensional CDW ordering appear. We also investigate the anisotropic character of the CDW-mediated scattering. We find that this is strongly anisotropic only close to the CDW quantum critical point (QCP) at low temperature and very low energy. It rapidly becomes nearly isotropic and marginal-Fermi-liquid-like away from the CDW QCP and at finite (even rather small) energies. This may reconcile the interpretation of Hall measurements in terms of anisotropic CDW scattering with recent photoemission experiments Bok, J.M., et al. Sci. Adv. 2, e1501329 (2016).}, 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} }