Department of Physics

Physics Theory Seminar

– Spring 2015

Division of Theoretical Physics at the Department of Physics organizes a series of theory seminars. Physics theory seminars are open.

Time: Monday 15:15 - 16:00

Location: E5-103, Realfagbygget NTNU. Natural Science Building

Coordinator: Jacob Linder

Theory seminars for the spring 2015

February 9

Ilya Eremin, Theoretische Physik III, Ruhr-Universität Bochum
«Superconductivity from repulsion in multiband layered systems: novel s-wave symmetry and potential time-reversal symmetry breaking in iron-based superconductors»

February 9

Ilya Eremin, Theoretische Physik III, Ruhr-Universität Bochum
«Superconductivity from repulsion in multiband layered systems: novel s-wave symmetry and potential time-reversal symmetry breaking in iron-based superconductors»

Abstract

Superconductivity from repulsion in multiband layered systems: novel s-wave symmetry and potential time-reversal symmetry breaking in iron-based superconductors

In my talk we will review the multiband aspects of superconductivity arising from repulsive interaction with weak spin fluctuations.

Most importantly, I will analyze the structure of the pairing interaction and superconducting gaps for LiFeAs, which electronic structure and superconducting gaps are well studied by ARPES. We use the ten-orbital tight-binding model, derived from ab-initio LDA calculations with hopping parameters extracted from the fit to ARPES experiments.

We find that the pairing interaction almost decouples between two subsets, one consists of the outer hole pocket and two electron pockets, which are quasi-2D and are made largely out of dxy orbital, and the other consists of the two inner hole pockets, which are quasi-3D and are made mostly out of dxz and dyz orbitals.

Furthermore, the bare inter-pocket and intra-pocket interactions within each subset are nearly equal. In this situation, small changes in the intra-pocket and inter-pocket interactions due to renormalizations by high-energy fermions give rise to a variety of different gap structures. Different s-wave gap configurations emerge depending on whether the renormalized interactions increase attraction within each subset or increase the coupling between particular components of the two subsets.

We argue that the state with opposite sign of the gaps on the two inner hole pockets has the best overlap with ARPES data.

February 16

Matthias Eschrig, Royal Holloway, University of London and NTNU (Lars Onsager Professorship 2015)
«Modern theory of polarization in solids - Berry phase approach: part I»

February 16

Matthias Eschrig, Royal Holloway, University of London and NTNU (Lars Onsager Professorship 2015)
«Modern theory of polarization in solids - Berry phase approach: part I»

Abstract

Modern theory of polarization in solids - Berry phase approach: part I

 

Mon, 26 Jan 2015 08:55:02 +0100

February 27

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Modern theory of polarization in solids - Berry phase approach: part II»

The seminar will take place on Friday February 27. at 10:15-12:00 in R10

February 27

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Modern theory of polarization in solids - Berry phase approach: part II»

The seminar will take place on Friday February 27. at 10:15-12:00 in R10

Abstract

Modern theory of polarization in solids - Berry phase approach: part II

Fri, 20 Feb 2015 14:13:42 +0100

March 23

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Topological materials and Majorana fermions: part I»

March 23

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Topological materials and Majorana fermions: part I»

Abstract

Topological materials and Majorana fermions: part I

 

March 30

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Topological materials and Majorana fermions: part II»

March 30

Matthias Eschrig, Royal Holloway, University of London and NTNU

«Topological materials and Majorana fermions: part II»

Abstract

Topological materials and Majorana fermions: part II

 

Mon, 26 Jan 2015 08:54:35 +0100
Tue, 10 Feb 2015 08:34:24 +0100
Irene Aspli