Shot noise in magnetic tunneling structures with two-level quantum dots

Abstract

We analyze shot noise in a magnetic tunnel junction with a two-level quantum dot attached to the magnetic electrodes. The considerations are limited to the case when some transport channels are suppressed at low temperatures. Coupling of the two dot's levels to the electrodes are assumed to be generally different and also spin dependent. To calculate the shot noise we apply the approach based on the full counting statistics. The approach is used to account for experimental data obtained in magnetic tunnel junctions with organic barriers. The experimentally observed Fano factors correspond to the super-Poissonian statistics, and also depend on relative orientation of the electrodes' magnetic moments. We have also calculated the corresponding spin shot noise, which is associated with fluctuations of spin current.

Waiting time distribution revealing the internal spin dynamics in a double quantum dot

“…In particular, the shot noise, resulting from charge quantization, was found to provide information about the statistics and charge of quasiparticles, or the presence of interactions [1]. Due to this fact, noise has already been widely studied, both experimentally and theoretically, in the variety of systems, including multilevel quantum dots [2][3][4][5], quantum dot spin valves [6][7][8], magnetic tunnel junctions [9][10][11], systems of capacitively coupled charge impurities [12], quantum dots [13] or metallic islands [14], quantum dot molecules [15][16][17], nanoelectromechanical systems [18], quantum dots strongly coupled to electromagnetic cavities [19], molecules with strong electron-vibrational coupling [20,21], quantum dots in the cotunneling [22][23][24] or Kondo [25][26][27][28] regimes, or systems realizing Majorana fermions [29].…”

Full counting statistics of the subsystem energy for free fermions and quantum spin chains

“…These kinds of distribution functions are examples of a more general concept known as full counting statistics (FCS) which studies the full distribution of a macroscopic observable in arbitrary systems. The term FCS was first popularized in the study of charge transport in mesoscopic systems [1][2][3][4][5][6][7][8][9]. However, since this quantity can be defined naturally in any quantum system, it has been also applied in different areas such as Fermi edge problems [10], ultracold atoms [11][12][13][14], quantum chains [15][16][17][18][19][20][21], and many-body localization [22,23].…”