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
Abstract:
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 [1], 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 [2] 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 [3].
[1] See e.g. Order, Disorder and Criticality. Advanced Problems of Phase Transition Theory. Yu.
Holovatch (editor). vol. 6, World Scientific, Singapore, 2020, 296 p.
[2] M. Krasnytska, B. Berche, Yu. Holovatch, R. Kenna. Entropy, 23(9) (2021) 1175.
[3] M. Dudka, M. Krasnytska, J. Ruiz-Lorenzo, Yu. Holovatch, 2022, in preparation.