OBAVIJEST
MARIJA VUČKOVIĆ
održat će znanstveni kolokvij (doktorski seminar) iz Fizike kondenzirane tvari pod naslovom
Mott insulator doping and resulting electronic phases in La2-xSrxCuO4
(Dopiranje Mottova izolatora i novonastale elektronske faze u La2-xSrxCuO4)
We present a single-crystal Cu nuclear magnetic resonance (NMR) study of the cuprate superconductor La2−xSrxCuO4 (LSCO) with hole-doping levels between x = 2% and 8%. By employing short spin echo times, we systematically investigate the local electronic spin environment in the region of the phase diagram where the material evolves from the antiferromagnetic Mott insulator parent phase to the superconducting state. As Sr concentration increases, at x = 5% we observe qualitative changes in both NMR spectra and relaxation times, which we interpret as signatures of a low-temperature transition from a state with disconnected metallic islands to a granular metal with tunnelling between the grains. Our results provide microscopic insight into the behaviour of a doped charge-transfer insulator in the presence of quenched substitutional disorder, indicating that a percolation-like connectivity transition occurs. This demonstrates that complex nanoscale electronic phase separation is ubiquitous in LSCO around the doping level where superconductivity first emerges. Additionally, fast nuclear quadrupole resonance (NQR) measurements were performed on in-house grown powder samples doped between x = 1.5 and 10%, for temperatures above 100 K. For x < 6 %, we observe signal wipe-out and peak frequency shift, which we attribute to the onset of enhanced spin fluctuations that lead to short relaxation times on the low frequency side of the spectral lines.
Seminar će se održati u petak 9. svibnja 2025. godine u 9:30 sati u predavaonici F-201 na Fizičkom odsjeku Prirodoslovno-matematičkog fakulteta.
Pozivaju se studenti doktorskog studija Fizike, smjer Fizika kondenzirane tvari da prisustvuju seminaru, ako nisu spriječeni.
Voditeljica smjera
Prof. dr. sc. Ana Akrap, v. r.
Pristupačnost
