## Spin and energy currents in integrable and nonintegrable spin-1/2 chains: A typicality approach to real-time autocorrelations

Autor(en): | Steinigeweg, Robin Gemmer, Jochen Brenig, Wolfram |

Stichwörter: | DYNAMICS; Materials Science; Materials Science, Multidisciplinary; MODEL; Physics; Physics, Applied; Physics, Condensed Matter; THERMAL-CONDUCTIVITY; TRANSPORT; XXZ CHAIN |

Erscheinungsdatum: | 2015 |

Herausgeber: | AMER PHYSICAL SOC |

Journal: | PHYSICAL REVIEW B |

Volumen: | 91 |

Ausgabe: | 10 |

Zusammenfassung: | We use the concept of typicality to study the real-time dynamics of spin and energy currents in spin-1/2 models in one dimension and at nonzero temperatures. These chains are the integrable XXZ chain and a nonintegrable modification due to the presence of a staggered magnetic field oriented in the z direction. In the framework of linear response theory, we numerically calculate autocorrelation functions by propagating a single pure state, drawn at random as a typical representative of the full statistical ensemble. By comparing to small-system data from exact diagonalization (ED) and existing short-time data from time-dependent density matrix renormalization group, we show that typicality is satisfied in finite systems over a wide range of temperature and is fulfilled in both integrable and nonintegrable systems. For the integrable case, we calculate the long-time dynamics of the spin current and extract the spin Drude weight for large systems outside the range of ED. We particularly provide strong evidence that the high-temperature Drude weight vanishes at the isotropic point. For the nonintegrable case, we obtain the full relaxation curve of the energy current and determine the heat conductivity as a function of magnetic field, exchange anisotropy, and temperature. |

ISSN: | 24699950 |

DOI: | 10.1103/PhysRevB.91.104404 |

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