Magnetism in Closed-shell Quantum Dots: Emergence of Magnetic Bipolarons

TL;DR

This paper predicts that closed-shell semiconductor quantum dots, traditionally considered nonmagnetic, can exhibit magnetism when doped with magnetic impurities, revealing a new magnetic ground state.

Contribution

It introduces the concept that magnetic impurities can induce magnetism in closed-shell quantum dots, challenging the assumption of their inherent nonmagnetic nature.

Findings

Emergence of a broken-symmetry magnetic ground state in doped closed-shell quantum dots.

Demonstration using a two-fermion model of the possibility of magnetism.

Proposals for experimental verification of magnetic behavior in such dots.

Abstract

Similar to atoms and nuclei, semiconductor quantum dots exhibit formation of shells. Predictions of magnetic behavior of the dots are often based on the shell occupancies. Thus, closed-shell quantum dots are assumed to be inherently nonmagnetic. Here, we propose a possibility of magnetism in such dots doped with magnetic impurities. On the example of the system of two interacting fermions, the simplest embodiment of the closed-shell structure, we demonstrate the emergence of a novel broken-symmetry ground state that is neither spin-singlet nor spin-triplet. We propose experimental tests of our predictions and the magnetic-dot structures to perform them.