{
  "id": "1710.09114",
  "version": "v1",
  "published": "2017-10-25T08:27:20.000Z",
  "updated": "2017-10-25T08:27:20.000Z",
  "title": "1/f Magnetization Noise at the Onset of Phase Transitions for Defect Sites in SQUIDs",
  "authors": [
    "Amrit De"
  ],
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "It is shown here that $1/f^\\alpha$ magnetization noise is manifestation of the onset of thermodynamic phase transitions for finite sized interfacial defects at the metal insulator interface in SQUIDs. The model comprises of clusters of interacting TLSs, likely due to color center defects. A random distribution of clusters and long range ferromagnetic interactions are shown to self consistently lead to flux noise where $\\alpha(T)\\lesssim 1$ over a range of temperatures in the ordered phase at the phase transition onset. The results are independent of system size and there are no prior assumptions made about the distribution of fluctuation rates. Like the experiments, the breaking of time reversal symmetry when $\\alpha\\sim 1$ is further confirmed through three-point correlations and flux-inductance-noise spectrum. A combination of Monte Carlo simulations and a recent method to calculate correlation functions is used in this study. The second method allows the systematic extraction of temperature dependent $n^{th}$-order correlation functions for $N$ arbitrary interacting two-level-systems(TLSs). Further, from the fluctuation dissipation theorem it is shown why the experimentally observed inductance noise is inherently temperature dependent while the flux noise is not. Analytical expressions allow simplified four-point correlation function calculations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-10-25T08:27:20.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "phase transition",
      "magnetization noise",
      "defect sites",
      "simplified four-point correlation function calculations",
      "temperature dependent"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}