Inaugural lecture by Arno Hiess

Is It Love? The Interplay of Magnetism and Superconductivity as seen by Neutrons

Neutron scattering is of particular importance to appreciate the interrelation of magnetism and superconductivity. They help answering the following essential questions: Are magnetism and superconductivity two different phenomena or manifestation of a new ground state? How can neutron spectroscopy reveal the symmetry of the corresponding order parameters? What are the energy scales relevant for the superconducting coupling mechanism?

During my lecture I will first present results from neutron diffraction experiments used to investigate static microscopic properties. They reveal details of the moment arrangement but also the spin and orbital contributions of the (paramagnetic) magnetic moment.

The spin dynamics in momentum and energy space can be studied by neutron spectroscopy. Upon entering the superconducting state the energy dependence of the dynamic response changes at selected momentum space positions, reflecting the opening of the superconducting gap.  I will present various examples from different classes of unconventional superconductors with an emphasis on cerium- and actinide-based intermetallic superconductors.

Those experiments profited from the latest neutron instrumentation at both ILL, Grenoble, France and FRM2, Munich, Germany and pave the way to future investigations. In the last part of my presentation I will present some challenges and discuss how those will be addressed with the instrumentation at the next generation neutron source ESS in Lund, Sweden.

About the speaker: Arno Hiess works for the European Spallation Source (ESS) as head of the Neutron Science Division and is in charge of developing ESS’s current and future neutron science environment. Arno Hiess, born 1967, studied physics and mathematics at the Technical Hochschule Darmstadt, where he graduated in 1993. Supervised by F. Steglich (TH Darmstadt) and G. H. Lander (ITU Karlsruhe) he moved to CEA/Grenoble for his PhD thesis research project on ‘neutron and x-ray investigations of competing magnetic interactions in strongly correlated metals’. Before integrating at ESS in 2011, Arno Hiess worked from 1997 to 2011 as a scientist at the Institut Laue – Langevin, where he was responsible for constructing and operating several triple-axis spectrometers. In 2003 and 2004 he was a visiting scientist at TU Dresden and MPI-CpfS, Dresden. There he also completed his habilitation on ‘microscopic insights into he magnetism and superconductivity of actinide-based intermetallic compounds’ in 2009.