Condensed Matter Physics
Research in condensed matter at Linnaeus University is done in the Condensed Matter Physics (CMP) research group. We deal primarily with theoretical studies of nanomagnetism, spintronics and molecular electronics.
Ongoing projects include nanospintronics at the atomic level with singlemolecule magnets in singleelectron transistors, magnetic impurities in semiconductor nanostructures and novel Dirac's materials such as graphene and topological insulators. These novel quantum systems can be employed for the physical realization of quantum computation. Thermoelectric transport in molecular junctions is also investigated.
The Condensed Matter Physics group is a part of the Department of Physics and Electrical Engineering at the Faculty of Technology. We are located on the third floor of the building Magna, Pedalstråket 11, in Kalmar, and in building B and D, Vejdes Plats 6, in Växjö.
Active projects
Below, please find a list of our active projects.
Nanomagnetism and molecular spintronics
This project investigates theoretically electric control of the magnetic properties of molecular magnets. Two classes of magnetic molecules are considered. The first class consists of molecules that are spin frustrated. As a consequence of the frustration, the groundstate manifold of these molecules is characterized by states of different spin chirality, which can be coupled by an external electric field. Electric control of these spin states can be used to encode and manipulate quantum information. The second class comprises molecules known as singlemolecule magnets, which are characterized by a high spin and a large magnetic anisotropy. Here the main goal is to control and manipulate the magnetic properties, such as the anisotropy barriers, by adding and subtracting individual electrons, as achieved in tunneling transport.
Key publications
Firstprinciples study of spinelectric coupling in a Cu3 single molecular magnet, MF Islam, JF Nossa, CM Canali, M Pederson
Firstprinciples studies of spinorbit and DzyaloshinskiiMoriya interactions in the Cu3 singlemolecule magnet, JF Nossa, MF Islam, CM Canali, MR Pederson
Electric control of a Fe4 singlemolecule magnet in a singleelectron transistor, JF Nossa, MF Islam, CM Canali, MR Pederson
Magnetic solotronics and dilute magnetism in semiconductor nanostructures
1) Magnetic solotronics on semiconductor surfaces
Solotronics (solitary dopant optoelectronics) aims at understanding and controlling the properties of individual dopants in a semiconductor host. It bears exciting prospects for novel spintronics devices at the atomic scale. In our work we develop quantum mechanical theories and models to investigate the following problems;
(i) electronic and magnetic properties of subsitutional transition metal impurities, such as Mn and Fe ions, positioned on the surface of GaAs ,
(ii) effect of external magnetic and electric fields on the magnetic anisotropy of single transitionmetal acceptors,
(iii) Timedependent spin dynamics of transitionmetal impurities and their bound acceptors and
(iv) Electric local manipulation of transitionmetal impurities by means of nearby charged defects on GaAs (110) surface.
Our theoretical tools range from atomistic tightbinding models to firstprinciples methods based on densityfunctional theory.
Key publications
Chern number spins of Mn acceptor magnets in GaAs, T.o. Strandberg, C.m. Canali and A.h. Macdonald
Magnetic interactions of substitutional Mn pairs in GaAs, Olof Strandberg, Carlo Canali and Allan Macdonald
Magnetic anisotropy of single Mn acceptors in GaAs in an external magnetic field, M. Bozkurt, M.R. Mahani, P. Studer, J.M. Tang, S. Schofield, N. Curson, M.e. Flatte, A.yu. Silov, C. F. Hirjibehedin, C.M. Canali and P.m. Koenraad
2) Dilute magnetic semiconductor nanowires
In collaboration with experimentalists of the Nanometer Structure Consortium at Lund University we investigate theoretically magnetotransport properties of Mnion implanted semiconductor nanowires.
Key publications
A new route toward semiconductor nanospintronics: highly Mndoped GaAs nanowires realized by ionimplantation under dynamic annealing conditions, NanoLett 11, 3935 (2011)
Hopping Conduction in Mn IonImplanted GaAs Nanowires, NanoLett 2012 (DOI: 10.1021/nl302318f)
Magnetic Polarons and Large Negative Magnetoresistance in GaAs Nanowires Implanted with Mn Ions, NanoLett, Article ASAP DOI: 10.1021/nl402229r
Topological insulators
Topological insulator (TI) materials [1] host on their boundaries a new type of topological states of quantum matter, which, unlike the Quantum Hall effect, exist without breaking of timereversal symmetry. Theoretical prediction and subsequent experimental demonstration of these topological states in both 2D and 3D systems have given rise to what is now one of the most exciting new directions in condensed matter physics. Apart from providing a test platform for some fundamental concepts in mathematics and physics, the study of topological insulators hold promise for novel applications in materials science, chemistry, spintronics and quantum computation. However, to be able to fully explore the potential of TIs, one is required to have a detailed knowledge of the nature and properties of topological surface states in real TI materials as well as a quantitative understanding of how they respond to external perturbations [2]. In laboratory, these questions can be addressed with advanced experimental probes, such as spinsensitive angleresolved photoemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM).
In our work, we investigate the properties of surface states in real 3D TIs theoretically by using advanced computational tools for atomistic modelling of materials. We have implemented a microscopic tightbinding model for bismuth selenide (Bi2Se3) family of 3D TIs, with parameters extracted from ab initio calculations. This constitutes a computationally feasible yet fully atomistic quantitative approach, which enables comparison with experiment. Our studies provide insight into spatial as well spin and orbital character of the wave function associated with the topological surface states, which is crucial for understanding the behaviour of real materials [3]. We also investigate finitesize effects on the surface states in Bi2Se3 films, related to finite thickness and finite (mesoscopic) sample size. Another topic of current interest is the interplay of topological surface states with timereversal breaking perturbations, such as external magnetic fields and magnetic dopants.
[1] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010); X.L. Qi and S.C. Zhang, Rev. Mod. Phys. 83, 1057 (2011)
[2] H. Beidenkopf et al., Nature Physics 7, 939 (2011); L. A. Wray et al., Nature Physics 7, 21 (2011)
[3] Cao et al., Nature Physics 9, 499 (2013)
Key publications
Probing the wave function of the surface states in Bi2Se3 topological insulator: a realistic tightbinding approach, Anna Pertsova and Carlo M. Canali
Theoretical studies of surface states in Bi2Se3: effects of finite thickness, finitecluster boundaries, and surface doping, A. Pertsova, M.R. Mahani, C.M. Canali, F. Islam and A.h. Macdonald
Theoretical studies of single magnetic impurities on the surface of semiconductors and topological insulators, M. R. Mahani, Anna Pertsova, C. M. Canali, M. F. Islam and A. H. Macdonald
Holonomic quantum computation
An overall goal of the project is to assess the feasibility of using geometric phases and quantum holonomies to build robust quantum gates, and investigate their behavior when the size of a quantum system grows, thereby gaining insights into largescale quantum computation.
Key publications
NonAbelian offdiagonal geometric phases in nanoengineered fourqubit systems, Vahid Azimi Mousolou, Carlo M. Canali and Erik Sjöqvist
Unifying geometric entanglement and geometric phase in a quantum phase transition, Vahid Azimi Mousolou, Carlo M. Canali and Erik Sjöqvist
Universal Nonadiabatic Holonomic Gates in Quantum Dots and SingleMolecule Magnets, Vahid Azimi Mousolou, Carlo M. Canali and Erik Sjöqvist
Thermoelectric transport and dynamics in molecular junctions
This project is focused on theoretical description of electron transport in nanoscale junctions.
Linnaeus Physics Colloquium
Linnaeus Physics Colloquium is a series of seminars delivered by renowned researchers in physics. The seminars normally take place in building Magna in Kalmar, but can also be attended through link in building D in Växjö, or live through Zoom, https://lnuse.zoom.us/j/416290322. Se each seminar below for information.
All seminars

Topological Metamaterials and Dynamical Phenomena in Magnets  All day

Global pointtopoint ionospheric ray tracing Seminarium

A derivation of the fluctuationdissipation theorem based on quantum electrodynamics Seminarium

Entanglement in quantum matter  thermalization and its absence Seminarium

Linnaeus Physics Colloquium: Scanning tunneling microscopy and photoemission studies of Ag films on metal/semiconductor surfaces Seminar

Linnaeus Physics Colloquium: Shape plasmonics, geometric eigenvalues and crystal field theory Seminar

Linnaeus Physics Colloquium: Spin on 2D electronics Seminar

Linnaeus Physics Colloquium: Topological quantum matter Seminar

Physics research seminar: Optimal plasmonic multipole resonances of a sphere in lossy media Seminar

Linnaeus Physics Colloquium: The Large Hadron Collider vs The Standard Model Seminar

Single molecule magnets: spin manipulation, intermolecular interactions and electronic structure Seminar

Linnaeus Physics Colloquium: Processes at molecular interfaces: opportunities and challenges in polymer solar cells Seminar

Linnaeus Physics Colloquium: Timeresolved adsorbatesurface and donoracceptor dynamics

Linnaeus Physics Colloquium: Molecular Beam Epitaxy – a way to fabricate and control crystalline materials at the nanoscale

Linnaeus Physics Colloquium: Exploring Nanostructures with Scanning Tunneling Microscopy
Staff
Active members
 Carlo Canali Professor, Subject Representative
 +46 48044 69 95
 carlocanalilnuse
 Cecilia Holmqvist Associate professor
 +46 48044 69 47
 ceciliaholmqvistlnuse
 Magnus Paulsson Associate professor
 +46 48044 63 08
 magnuspaulssonlnuse
 Pavel Bessarab Senior lecturer
 +46 48044 67 78
 pavelbessarablnuse
 Shahid Sattar Postdoctoral fellow
 +46 48049 70 60
 shahidsattarlnuse
Alumni
 Anna Pertsova, Postdoc, anna.pertsova@lnu.se
 Elena Tagliabue, Master Student, et222gp@student.lnu.se
 M Reza Mahani, Doctoral Student, current position: Postdoc, reza.mahani@lnu.se
 Faluke Aikebaier, Master Student, current position: Doctoral Student at the University of Jyväskylä, fa222eb@student.lnu.se
 Vahid Azimi Mousolou, Doctoral Student, current position: Lecturer
 Javier Nossa, Doctoral Student, current position: Postdoc
 Shirin Hakimi, Master Student, sh22ej@student.lnu.se
 Olof Strandberg, Doctoral Student
 Lukasz Michalak, Doctoral Student