Johannes Knolle

Dr Johannes Knolle

Office: 516 Mott Bld
Phone: +44(0)1223 3 37238
Email: jk628 @ cam.ac.uk

TCM Group, Cavendish Laboratory
19 JJ Thomson Avenue,
Cambridge, CB3 0HE UK.

Research

My research specializes in theoretical condensed matter physics. In particular, my work is focused on three main topics:

Frustrated magnetism and quantum spin liquids
Non-equilibrium behavior of quantum systems
Unconventional superconductivity

In general, I study problems which can be directly compared with experimental data. For example, I have recently addressed the question: How to probe fractionalized quasiparticles of a quantum spin liquid in experiments? Our exact calculation of the dynamic spin structure factor of a two dimensional quantum spin liquid shows that salient signatures of quantum number fractionalization are visible in dynamical response functions which are directly accessible in standard experiments, e.g. by inelastic neutron or Raman scattering.

In Plain English

In condensed matter physics complex behavior arises from the interaction of a large number of basic degrees of freedom. It is fascinating to uncover the richness of this behavior, and to understand the universal principles that organize the physical world. One of the established principles is the Landau theory whereby states of matter are classified according to their broken symmetries. In recent years distinct ways were uncovered showing how this description can break down. My research is focused on condensed matter systems out of equilibrium and beyond the Landau paradigm in regimes in which the laws of quantum mechanics are important.

Featured Publications

Dynamics of a Two-Dimensional Quantum Spin Liquid: Signatures of Emergent Majorana Fermions and Fluxes J. Knolle, D. L. Kovrizhin, J. T. Chalker, and R. Moessner Phys. Rev. Lett. 112 207203 (2014) Featured with a Viewpoint in Physics by A. M. Tsvelik Physics 7, 54 (2014)
Raman Scattering Signatures of Kitaev Spin Liquids in A2IrO3 Iridates with A=Na or Li J. Knolle, Gia-Wei Chern, D. L. Kovrizhin, R. Moessner, and N. B. Perkins Phys. Rev. Lett. 113 187201 (2014)
The Antiferromagnetic Phase of Iron-Based Superconductors: An Itinerant Approach J. Knolle, and I. Eremin Invited Review Chapter in Iron-based Superconductors (2013) Edited by N.-L. Wang, H. Hosono and Pengcheng Dai, Pan Stanford Publishing Pte. Ltd., Singapore 2013
Magnetic resonance from the interplay of frustration and superconductivity J. Knolle, I. Eremin, J. Schmalian, R. Moessner Phys. Rev. B 84 180510 (Rapid) (2011)
Quasiparticle Interference in the Spin-Density Wave Phase of Iron-Based Superconductors J. Knolle, I. Eremin, A. Akbari, and R. Moessner Phys. Rev. Lett. 104 257001 (2010)
Theory of itinerant magnetic excitations in the spin-density-wave phase of iron-based superconductors J. Knolle, I. Eremin, A. V. Chubukov, and R. Moessner Phys. Rev. B 81 140506 (Rapid) (2010)