Fractalization drives crystalline states in a frustrated spin system

TL;DR

This paper demonstrates that a sequence of magnetization plateaux in a frustrated spin system can be explained by the Hofstadter problem with interactions, revealing fractal-like crystalline states driven by lattice effects.

Contribution

It provides the first experimental observation of quantum Hall-like plateaux in a frustrated spin system and models them using the Hofstadter problem with interactions.

Findings

Sequence of magnetization plateaux observed at specific fractions.

Hofstadter model with interactions reproduces the observed plateaux.

Evidence of fractal crystalline states in a frustrated spin system.

Abstract

We measure a sequence of quantum Hall-like plateaux at 1/q: 9 >= q >= 2 and p/q = 2/9 fractions in the magnetisation with increasing magnetic field in the geometrically frustrated spin system SrCu2(BO3)2. We find that the entire observed sequence of plateaux is reproduced by solving the Hofstadter problem on the system lattice when short-range repulsive interactions are included, thus providing a sterling demonstration of bosons confined by a magnetic and lattice potential mimicking fermions in the extreme quantum limit.