Mailman 3 March 2021 - Kwant-discuss

Superconductor as a lead vs superconudctor in the scattering region
by Henry Axt March 21, 2021

March 21, 2021

This is more of a physical question. I am considering a system set up of a superconductor connected to a non-superconducting metal. As in: [Lead][Conductor][Superconductor] In Kwant I set the superconductor up with an electron lattice and a hole lattice. I can simulate this is two ways; one is the superconductor as a lead, and the other is the superconductor as part of the scattering system. So, [Lead][Conductor Region][Superconducting Lead] or [Lead][Conductor Region][Superconductor Region] If I look at the conduction between the electron and the hole lead on the left leads, I simulate slightly different conduction values for the case of the SC in the scattering region and the SC as a lead on the right side. Physically, as I understand it, there should be basically no difference at least at low enough energy values. Is the slight difference due to this "low enough energy" threshold, or am I missing something physical or numerical from kwant that would cause this difference to exist regardless?

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using conservation law
by Adel Belayadi March 10, 2021

March 10, 2021

Dear Kwant user,Good day. I am notgetting the idea where and where not to use theconservation_lw=-sigma_z in spinful Hamiltonian. For instance in theTutorial 2.3.2. Spatially dependent values through functions, thehamiltanian is spinful but the conservation law was not set while computing the conductance. The same thing in the tutorial of Quantumanomalous Hall effect where the local current is plotted without highlighting the conservation law. However, in the case of magnetic texture tutorial the conservation law was set as-sigma_z. Additionally, in some discussion ( kwant mailing list) about up/down conduction you have urged to set the conservation law to be-sigma_z instead of using two different lattices (up-lattice ansdown-lattice). My question is why we have not used the conservation law in the first two examples. In fact, I am calculating the current flow in a region where I have included some interactions such as intrinsic spin-orbit coupling, Rashba SOC and Pseudo inversion asymmetric SOC. So do I need to provide the type of conservation law or not. Additionally, is there a way to calculate the current in parallel since the energy isone value. I mean the current for a given energy. So I am not getting the idea how to set parallel calculation in the case of current. I do thank for your time and support Regards Adel BELAYADI

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2D Heterostructure creation using quant.
by Ritwick Sarkar March 1, 2021

March 1, 2021

Hello all, I am interested to work with quantum transport using kwant in 2D heterostructure. I want to create mono and bilayer of MoS2, and also introduce doping of oxygen in that. For that reason, I am seeking help from your group as it is not available in the API. waiting for your reply, ****************************** With regards, Ritwick Sarkar. ******************************* *******************************

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