Quantum oscillation and the Aharonov-Bohm effect in a multiply connected normal-conductor loop

ABSTRACTDuring the last few years, it became clear that electron interference phenomena strongly modify the conductance of disordered systems. In thin metal films, this interference produces an anomalous low temperature magneto-resistance which enables to obtain detailed information about the inelastic, spin-orbit and magnetic scattering mechanisms. In a multiply-connected geometry, the interference leads to magnetoresistance oscillations. In long metal cylinders, only the oscillations which are not destroyed by impurity averaging, can be observed (flux period h/2e). In single loops, the original Aharonov-Bohm oscillations with flux period h/e are also present. A review will be presented of recent experimental results obtained for quasi two-dimensional plane films, cylinders, rings and arrays.

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NOVEL INTERFERENCE EFFECTS IN MULTIPLY CONNECTED NORMAL METAL RINGS

Modern Physics Letters B ◽

10.1142/s0217984994000303 ◽

1994 ◽

Vol 08 (05) ◽

pp. 301-310 ◽

Cited By ~ 20

Author(s):

A.M. JAYANNAVAR ◽

P. SINGHA DEO

Keyword(s):

Quantum Interference ◽

Normal Metal ◽

Quantum Mechanical ◽

Small Field ◽

Interference Effects ◽

Multiply Connected ◽

Small Magnetic Field ◽

Metal Rings ◽

Bohm Effect ◽

Aharonov Bohm

We have investigated the magnetoconductance of a normal metal loop connected to ideal wires in the presence of magnetic flux. The quantum mechanical potential, V, in the loop is much higher than that in the connecting wires (V=0). The electrons with energies less than the potential height on entering the loop propagate as evanescent modes. In such a situation, the contribution to the conductance arises from two non-classical effects, namely, Aharonov-Bohm effect and quantum tunneling. For this case we show that, on application of a small magnetic field, the conductance initially always decreases, or small field magnetoconductance is always negative. This is in contrast to the behavior in the absence of the barrier, wherein the small field magnetoconductance is either positive or negative depending on the Fermi energy and other geometric details. We also discuss the possibility of a better switch action based on quantum interference effects in such structures.

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Phenomena and devices at the quantum scale and the mesoscale

10.1093/oso/9780198759874.003.0003 ◽

2017 ◽

Author(s):

Sandip Tiwari

Keyword(s):

Coulomb Blockade ◽

Secure Communication ◽

Quantum Hall ◽

Nanoscale Device ◽

Self Energy ◽

Stability Diagrams ◽

Charge Stability ◽

Bohm Effect ◽

Aharonov Bohm ◽

Non Locality

Unique nanoscale phenomena arise in quantum and mesoscale properties and there are additional intriguing twists from effects that are classical in origin. In this chapter, these are brought forth through an exploration of quantum computation with the important notions of superposition, entanglement, non-locality, cryptography and secure communication. The quantum mesoscale and implications of nonlocality of potential are discussed through Aharonov-Bohm effect, the quantum Hall effect in its various forms including spin, and these are unified through a topological discussion. Single electron effect as a classical phenomenon with Coulomb blockade including in multiple dot systems where charge stability diagrams may be drawn as phase diagram is discussed, and is also extended to explore the even-odd and Kondo consequences for quantum-dot transport. This brings up the self-energy discussion important to nanoscale device understanding.

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