50 years of correlations with Michael Fisher and the renormalization group

TL;DR

This paper reviews the author's personal and scientific interactions with Michael Fisher, discusses recent renormalization group studies on complex magnetic systems, and highlights open issues in the field.

Contribution

It provides a personal account combined with recent research insights into renormalization group applications in magnetism and critical phenomena.

Findings

Insights into dipole-dipole interactions in magnets

Discussion of bicritical points in phase diagrams

Open questions in the random field Ising model

Abstract

This paper will be published in ``50 years of the renormalization group", dedicated to the memory of Michael E. Fisher, edited by Amnon Aharony, Ora Entin-Wohlman, David Huse, and Leo Radzihovsky, World Scientific. I start with a review of my personal and scientific interactions with Michael E. Fisher, who was my post-doc mentor in 1972-1974. I then describe several recent renormalization group studies, which started during those years, and still raise some open issues. These include the magnets with dipole-dipole interactions, the puzzle of the bicritical points and the random field Ising model.