@article{986,
  abstract     = {The many-body localization transition (MBLT) between ergodic and many-body localized phases in disordered interacting systems is a subject of much recent interest. The statistics of eigenenergies is known to be a powerful probe of crossovers between ergodic and integrable systems in simpler examples of quantum chaos. We consider the evolution of the spectral statistics across the MBLT, starting with mapping to a Brownian motion process that analytically relates the spectral properties to the statistics of matrix elements. We demonstrate that the flow from Wigner-Dyson to Poisson statistics is a two-stage process. First, a fractal enhancement of matrix elements upon approaching the MBLT from the delocalized side produces an effective power-law interaction between energy levels, and leads to a plasma model for level statistics. At the second stage, the gas of eigenvalues has local interactions and the level statistics belongs to a semi-Poisson universality class. We verify our findings numerically on the XXZ spin chain. We provide a microscopic understanding of the level statistics across the MBLT and discuss implications for the transition that are strong constraints on possible theories.},
  author       = {Serbyn, Maksym and Moore, Joel},
  issn         = {2469-9969},
  journal      = {Physical Review B - Condensed Matter and Materials Physics},
  number       = {4},
  publisher    = {American Physical Society},
  title        = {{Spectral statistics across the many-body localization transition}},
  doi          = {10.1103/PhysRevB.93.041424},
  volume       = {93},
  year         = {2016},
}

@article{987,
  abstract     = {In contrast to bulk FeSe, which exhibits nematic order and low temperature superconductivity, highly doped FeSe reverses the situation, having high temperature superconductivity appearing alongside a suppression of nematic order. To investigate this phenomenon, we study a minimal electronic model of FeSe, with interactions that enhance nematic fluctuations. This model is sign problem free, and is simulated using determinant quantum Monte Carlo (DQMC). We developed a DQMC algorithm with parallel tempering, which proves to be an efficient source of global updates and allows us to access the region of strong interactions. Over a wide range of intermediate couplings, we observe superconductivity with an extended s-wave order parameter, along with enhanced, but short-ranged, q=(0,0) ferro-orbital (nematic) order. These results are consistent with approximate weak-coupling treatments that predict that nematic fluctuations lead to superconducting pairing. Surprisingly, in the parameter range under study, we do not observe nematic long-range order. Instead, at stronger coupling an unusual insulating phase with q=(π,π) antiferro-orbital order appears, which is missed by weak-coupling approximations.},
  author       = {Dumitrescu, Philipp and Serbyn, Maksym and Scalettar, Richard and Vishwanath, Ashvin},
  issn         = {2469-9969},
  journal      = {Physical Review B},
  number       = {15},
  publisher    = {American Physical Society},
  title        = {{Superconductivity and nematic fluctuations in a model of doped FeSe monolayers: Determinant quantum Monte Carlo study}},
  doi          = {10.1103/PhysRevB.94.155127},
  volume       = {94},
  year         = {2016},
}

@article{1742,
  abstract     = {The effects of substrate temperature, growth rate, and postgrowth annealing on the composition of Ge islands grown on Si(001) were investigated with a combination of selective wet chemical etching and atomic force microscopy. A simple kinetic model comprising only surface diffusion processes can explain all the experimentally observed compositional profiles for pyramid and dome islands grown in the 560-620°C range. From this model three-dimensional compositional maps were extracted. By performing annealing experiments a change in the composition of the domes was observed. This could be explained as the result of the islands' movement induced by alloying-driven energy minimization. Also in this case kinetically hindered bulk diffusion processes are not needed to explain the experimental observations.},
  author       = {Katsaros, Georgios and Costantini, Giovanni and Stoffel, Mathieu and Esteban, Rubén and Bittner, Alexander and Rastelli, Armando and Denker, Ulrich and Schmidt, Oliver and Kern, Klaus},
  issn         = {2469-9969},
  journal      = {Physical Review B - Condensed Matter and Materials Physics},
  number       = {19},
  publisher    = {American Physical Society},
  title        = {{Kinetic origin of island intermixing during the growth of Ge on Si (001)}},
  doi          = {10.1103/PhysRevB.72.195320},
  volume       = {72},
  year         = {2005},
}