- 世話人 --- 小手川 恒
講演題目： Probing spin-correlated quantum matter with electron spin resonance spectroscopy
講師：Dr. Vladislav Kataev (Leibniz Institute for Solid State and Materials Research IFW Dresden, Germany)
Magnetic transition metal ions located at the regular sites of a crystalline solid may build up strongly correlated spin networks of different spatial dimensionality. Depending on the specifics of the chemical bonding and certain geometrical constraints, zero-dimensional (OD) spin clusters, 1D spin chains and ladders, 2D spin planes, or even more complex 3D spin structures can be realized in a number of materials.
An interplay between spin, orbital, charge and lattice degrees of freedom in these strongly correlated quantum magnets yields such spectacular phenomena as high temperature superconductivity, colossal magnetoresistance, multiferroic order, metal-insulator and quantum phase transitions, quantum spin liquid states, magnetic memory effects and others. For all these reasons the field of quantum magnetism in condensed matter physics is continuously expanding and currently attracts a lot of interdisciplinary interest.
High magnetic field electron spin resonance (ESR) spectroscopy has emerged as an instructive tool to investigate the low-energy spin dynamics, energy spectrum of the spin states and the spin structure of the ordered phases in a broad class of strongly correlated spin systems, which is of paramount importance for the comprehensive understanding of the above mentioned phenomena. In this talk, recent experiments conducted at the IFW Dresden on quasi-2D van der Waals crystals of α-RuCl3 will be discussed with a particular focus on the properties of the novel, magnetic field-induced spin liquid phase where signatures of unconventional fractionalization of magnetic excitations into the elusive Majorana fermions have been obtained.