arXiv subjects

L. Soriano

Publications and source records attributed to L. Soriano.

4 recordsLinked to original sources

arXiv2026

Singular spin fluctuations in the strange-metal phase of La2-xSrxCuO4

Although spin fluctuations are central to the physics of high-Tc cuprates, their relevance to strange-metal behavior in the overdoped regime remains unclear. Here, we use high magnetic fields to suppress superconductivity and an NMR protocol tailored to electronic inhomogeneity to show that the low-energy limit of the dynamical spin susceptibility χ''(q,omega) at x=0.25 in La2-xSrxCuO4 increases continuously down to our lowest temperatures. This behavior is suggestive of quantum-critical fluctuations, a leading candidate mechanism for strange-metal transport, yet is observed well beyond the spin-stripe critical doping x=0.19. Our data further reveal that the spin dynamics are spatially inhomogeneous, suggesting that nanoscale electronic inhomogeneity may underlie this apparent paradox. These observations provide new insight into the electronic state from which strange-metal behavior emerges.

cond-mat.supr-con↗

arXiv2025

Exploring electron spin dynamics in spin chains using defects as a quantum probe

We investigate the quantum dynamics of the electron spin resonance of topological defects (edge state) in dimerized chains. These objects are discontinuities of the spin chain protected by the properties of the global system leading to a quantum many-body multiplet protected from the environment decoherence. Despite recent achievements in the realization of isolated and finite spin chains, the potential implementation in quantum devices needs the knowledge of the relaxation and decoherence sources. Our study reveals that electron spin lattice relaxation is governed at lowest temperatures by phonon-bottlenecked process and at high temperature by the chain dimerization gap. We show that the inter edge-state effective dipolar field is reduced by the intrachain exchange coupling leading to a longer coherence time than isolated ions at equivalent concentration. Ultimately, we demonstrate that the homogeneous broadening is governed by the intra-chain dipolar field, and we establish design principles for optimizing coherence in future materials.

cond-mat.str-el↗

arXiv2020

Electron Spin Resonance of Defects in Spin Chains. o-(DMTTF)2X : a versatile system behaving like molecular magnet

The paper presents the Electron Paramagnetic Resonance study of defects in the spin chain o- (DMTTF)2X family using continuous wave and pulsed techniques. The defects in spin chains are strongly correlated and present similar microscopic structure as a molecular magnet. By means of 2D-HYSCORE and DFT calculations we show a strong reduction of hyperfine coupling between the defects and the nuclear spin bath. We assume that the reduction is due to the Heisenberg exchange interaction which screens the effect of the nuclei.

cond-mat.str-el↗

arXiv2019

Coherent spin dynamics of solitons in the organic spin chain compounds ($o$-DMTTF)$_2X$ ($X$ = Cl, Br)

We studied the magnetic properties, in particular dynamics, of the correlated spins associated with natural defects in the organic spin chain compounds ($o$-DMTTF)$_2X$ ($X$ = Br, Cl) by means of electron spin resonance (ESR) spectroscopy. Both materials exhibit spin-Peierls transitions at temperatures around 50 K [P. Foury-Leylekian et al. Phys. Rev. B 84, 195134 (2011)], which allow a separation of the properties of defects inside the chains from the magnetic response of the spin chains. Indeed, continuous wave ESR measurements performed over a wide temperature range evidence the evolution of the spin dynamics from being governed by the spins in the chains at elevated temperatures to a low-temperature regime which is dominated by defects within the spin-dimerized chains. Such defects polarize the antiferromagnetically coupled spins in their vicinity, thereby leading to a finite local alternating magnetization around the defect site which can be described in terms of a soliton, i.e. a spin 1/2 quasiparticle built of many correlated spins, pinned to the defect. In addition, contributions of triplon excitations of the spin-dimerized state to the ESR response below the transition temperature were observed which provides a spectroscopic estimate for the spin-gap of the studied systems. Moreover, details of spin dynamics deep in the spin-Peierls phase were investigated by pulse ESR experiments which revealed Rabi-oscillations as signatures of coherent spin dynamics. From a comparison of the characteristic damping times of the Rabi oscillations with measurements of the spin relaxation times by means of primary-echo decay and CPMG methods it becomes evident that inhomogeneities in local magnetic fields strongly contribute to the soliton decoherence.

cond-mat.str-el↗