This talk will be presented by CSH guest researcher Yurij Holovatch (Institute for Condensed Matter Physics, National Acad. Sci. of Ukraine) on Thursday, June 30 at 3 pm at the Complexity Science Hub.
Title: Criticality of structurally disordered magnets from the complex system science perspective
I will discuss the problem of influence of structural disorder on criticality. As a case study, we consider an impact of a weak quenched disorder on a magnetic phase transition. Taken that this problem itself has a long history , I summarize it in a brief introduction and afterwards I will concentrate on the main question of interest for us. Usually, such an impact is analyzed for a twocomponent mixture (e.g. a solid solution of a magnet with its non-magnetic counterpart).
A distinct feature of our analysis is consideration of changes in the magnetic phase transition when both components are magnets. To this end, we make use of a generalized Ising model suggested recently  in a context of complex systems. We show that this is the structural disorder itself that causes changes in the universal critical behaviour, regardless of whether it has a form of a random mixture of magnetic and non-magnetic constituents or of two different magnetic compounds .
 See e.g. Order, Disorder and Criticality. Advanced Problems of Phase Transition Theory. Yu.
Holovatch (editor). vol. 6, World Scientific, Singapore, 2020, 296 p.
 M. Krasnytska, B. Berche, Yu. Holovatch, R. Kenna. Entropy, 23(9) (2021) 1175.
 M. Dudka, M. Krasnytska, J. Ruiz-Lorenzo, Yu. Holovatch, 2022, in preparation.