Searcharxiv⌕ Search

arXiv subjects

J. Tworzydlo

Publications and source records attributed to J. Tworzydlo.

39 records · Page 3Linked to original sources

Non-Cayley-tree model for quasiparticle decay in a quantum dot

The decay of a quasiparticle in a confined geometry, resulting from electron-electron interactions, has been mapped onto the single-electron problem of diffusion on a Cayley tree by Altshuler et al. [Phys.Rev.Lett. 78, 2803 (1997)]. We study an alternative model, that captures the strong correlations between the self-energies of different excitations with the same number of quasiparticles. The model has a recursion relation for the single-particle density of states that is markedly different from the Cayley tree. It remains tractable enough that sufficiently large systems can be studied to observe the localization transition in Fock space predicted by Altshuler et al.

cond-mat.mes-hall↗

Spin-only approach to quantum magnetism in the ordered stripe state

It has been argued that the spin-dynamics in cuprate superconductors is governed by the proximity to a zero-temperature critical point. This critical point would be related to a transition from the superconducting phase to an ordered stripe state. Using a coupled spin-ladder model, we investigate to what extent the strong quantum spin-fluctuations in the ordered stripe state can be attributed to the spin sector. For the bond-centered stripes, we find that our spin-only model can account for the observed spin-fluctuations. For site-ordered stripes, coupling of the spin and charge sector is needed.

cond-mat.str-el↗

Quantum magnetism in the stripe phase: bond- versus site order

It is argued that the spin dynamics in the charge-ordered stripe phase might be revealing with regards to the nature of the anomalous spin dynamics in cuprate superconductors. Specifically, if the stripes are bond ordered much of the spin fluctuation will originate in the spin sector itself, while site ordered stripes require the charge sector as the driving force for the strong quantum spin fluctuations.

cond-mat.str-el↗