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<< /S /GoTo /D (section*.24) >> However, the conductance … endobj 41 0 obj While it is agreed upon that the 0,7 anomaly arises from electron-electron interactions, the high number of theoretical attempts at an explanation indicates that the detailed microscopic origin of the peculiar shoulder is still subject to controversal discussions.

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Nature Publishing Group 73 0 obj endobj (Nonequilibrium SOPT) Electronic transport in quasi-1D systems is essentially studied in quantum-point contact (QPC) and quantum-wire structures. endobj

This thesis aims at shedding light on the microscopic origin of a phenomenon in the field of semiconductor nanostructures, which occurs in transport through a short and narrow quasi one-dimensional constriction, the quantum point contact (QPC). The space of such maps is When a theory contains an odd number of flavors of chiral fermions, the actions of gauge symmetries in the identity component and the disconnected component of the gauge group on a physical state differ by a sign. Here, we present a microscopic model that qualifies to meet this requirement. << /S /GoTo /D (section*.17) >> << /S /GoTo /D (section*.46) >> Proposed theoretical explanations have invoked spontaneous spin polarization, ferromagnetic spin coupling, the formation of a quasi-bound state leading to the Kondo effect, Wigner crystallization and various treatments of inelastic scattering. endobj

120 0 obj 108 0 obj In other words, the gauge symmetries are in one-to-one correspondence with maps from the 4-sphere to the 3-sphere, which is the group manifold of SU(2). (Zero-temperature limit)

We calculate properties of our interacting one-dimensional QPC model using two methods: A specially developed approximation scheme within the functional renormalization group (fRG) provides reliable results for the magnetic field dependence of the 0.7 anomaly at zero temperature. 136 0 obj 64 0 obj << /S /GoTo /D (section*.27) >> endobj 164 0 obj 44 0 obj 60 0 obj (Methods Summary) endobj

endobj We find good qualitative agreement between theoretical calculations and experimental results on the dependence of the conductance on gate voltage, magnetic field, temperature, source-drain voltage (including the zero-bias peak) and interaction strength. 76 0 obj Microscopic Origin of the 0.7-Anomaly in Quantum Point Contacts Florian Bauer1;2, Jan Heyder1;2, Enrico Schubert1, David Borowsky1, Daniela Taubert1, Benedikt Bruognolo1;2, Dieter Please enable it to take advantage of the complete set of features! (Bare local density of states \(LDOS\)) (Conclusions) The 0.7 anomaly in quantum point contacts. 49 0 obj 84 0 obj endobj Nature Publishing Group A model system that demonstrates an anomaly in quantum phases. (Comparison: bare LDOS of QPC and QD)

endobj (Geometry-dependence of interaction U) << /S /GoTo /D (section*.2) >> (Model I) << /S /GoTo /D (section*.13) >> << /S /GoTo /D (section*.1) >> << /S /GoTo /D [186 0 R /Fit] >> (Compressibility and charge susceptibility) A global anomaly can also mean that a non-perturbative global anomaly cannot be captured by one loop or any loop perturbative Feynman diagram calculations --- examples include The most prevalent global anomaly in physics is associated with the violation of As these symmetries vanish at infinity, they cannot be constrained by boundary conditions and so must be summed over in the path integral. 80 0 obj

However, the Kondo origin of this anomaly remainsunder debate,and additional experimental evidenceis necessary.Herewereport onthe first phase- 2002 Nov 4;89(19):196802. doi: 10.1103/PhysRevLett.89.196802. (Comparison of dynamic and static fRG) << /S /GoTo /D (section*.42) >> 32 0 obj endobj Thus we see that the group of gauge transformations vanishing at infinity in Minkowski 4-space is This is the group which consists of a continuous choice of a gauge transformation in SU(2) for each point on the 4-sphere. 160 0 obj Name must be less than 100 characters 45 0 obj endobj Since SOPT's validity is restricted to weaker interaction strength, where calculations clearly show the right trend but not yet the full manifestation of the 0.7 anomaly, we are currently setting up an extension of our fRG approach within the Keldysh formalism, which will allow us to also explore finite excitation energies. 53 0 obj (fRG Flow equations) << /S /GoTo /D (section*.39) >> 72 0 obj

161 0 obj 133 0 obj endobj 29 0 obj Epub 2002 Oct 21.Sci Rep. 2019 Feb 13;9(1):1909. doi: 10.1038/s41598-018-37967-9.Edlbauer H, Takada S, Roussely G, Yamamoto M, Tarucha S, Ludwig A, Wieck AD, Meunier T, Bäuerle C.Nat Commun.

The linear conductance of a point contact, when measured as function of its channel width, is quantized in units of GQ = 2e(2)/h, where e is the electron charge and h is Planck's constant.

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