Speaker
Description
Dipolar interactions play an important role in the critical behavior of isotropic magnets. While the microscopic physics is usually dominated by short-range exchange interactions, dipolar interactions are strongly relevant in the RG sense due to their long-range nature, leading to a crossover from O(N) universality towards the dipolar fixed point, as pointed out by Aharony and Fisher in the early 1970s. The situation is much less clear in the presence of screening effects, which for example appear in antiferromagnets. In this regime, the long-range part of the interaction is suppressed and the surviving short-range term is canonically marginal. We investigate the fate of this term at classical and quantum phase transitions within a functional renormalization group approach. In accordance with previous perturbative results, we find it to be marginally irrelevant and provide a first estimate of the corresponding critical exponent. We discuss implications for rotational symmetry breaking in arbitrary isotropic systems, as well as consequences for systems with lower symmetry, like cubic magnets or electronic nematicity.
| Affiliation | Max Planck Institute for Solid State Research, Technische Universität München |
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| Career status | PhD student |