Finn Lasse Buessen

Hi, I am a theoretical physicist working on condensed matter systems. Currently, I am a postdoctoral fellow at the University of Toronto, working with Yong-Baek Kim and Arun Paramekanti. You can find me at

Department of Physics

University of Toronto

60 St. George Street

Toronto, Ontario M5S1A7


Office: MP1023

Phone: +1 (416) 978-1546

Email: fbuessen (at)

Research Interests

I am interested in the theory of strongly correlated systems, frustrated quantum magnetism, and the formation of quantum spin liquids. I have a strong background in software development and high-performance computing, which I leverage in my research to push the limits of modern computational physics.

At the moment I am working on state-of-the-art (pseudo-fermionic) functional renormalization group implementations that have proven to be powerful tools in the exploration of frustrated quantum magnetism, especially in three spatial dimensions.

Brief CV

since 10/2019
Postdoctoral fellow at University of Toronto
Ph.D. at University of Cologne (working with Simon Trebst)
M.Sc. at University of Cologne


Finn Lasse Buessen

A Functional Renormalization Group Perspective on Quantum Spin Liquids in Three-Dimensional Frustrated Magnets

Ph.D. thesis, University of Cologne (2019)

Dominik Kiese, Finn Lasse Buessen, Ciarán Hickey, Simon Trebst, and Michael M. Scherer

Emergence and stability of spin-valley entangled quantum liquids in moiré heterostructures


A. Revelli, M. Moretti Sala, G. Monaco, C. Hickey, P. Becker, F. Freund, A. Jesche, P. Gegenwart, T. Eschmann, F. L. Buessen, S. Trebst, P. H. M. van Loosdrecht, J. van den Brink, and M. Grüninger

Fingerprints of Kitaev physics in the magnetic excitations of honeycomb iridates


Finn Lasse Buessen, Vincent Noculak, Simon Trebst, and Johannes Reuther

Functional renormalization group for frustrated magnets with nondiagonal spin interactions

Phys. Rev. B 100, 125164 (2019)

A. Revelli, C.C. Loo, D. Kiese, P. Becker, T. Fröhlich, T. Lorenz, M. Moretti Sala, G. Monaco, F.L. Buessen, J. Attig, M. Hermanns, S.V. Streltsov, D.I. Khomskii, J. van den Brink, M. Braden, P.H.M. van Loosdrecht, S. Trebst, A. Paramekanti, and M. Grüninger

Spin-orbit entangled j=1/2 moments in Ba2CeIrO6 - a frustrated fcc quantum magnet

Phys. Rev. B 100, 085139 (2019)

Finn Lasse Buessen, Max Hering, Johannes Reuther, and Simon Trebst

Quantum spin liquids in frustrated spin-1 diamond antiferromagnets

Phys. Rev. Lett. 120, 057201 (2018)

Finn Lasse Buessen, Dietrich Roscher, Sebastian Diehl, and Simon Trebst

Functional renormalization group approach to SU(N) Heisenberg models: Real-space RG at arbitrary N

Phys. Rev. B 97, 064415 (2018)

Dietrich Roscher, Finn Lasse Buessen, Michael M. Scherer, Simon Trebst, and Sebastian Diehl

Functional renormalization group approach to SU(N) Heisenberg models: Momentum-space RG for the large-N limit

Phys. Rev. B 97, 064416 (2018)

Finn Lasse Buessen and Simon Trebst

Competing magnetic orders and spin liquids in two- and three-dimensional kagome systems: Pseudo-fermion functional renormalization group perspective

Phys. Rev. B 94, 235138 (2016)

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