Experiments on the ferromagnetic behavior of atomic repulsive Fermi gases

Year: 2017

Authors: Amico A.

Autors Affiliation: Univ Firenze, LENS, Sesto Fiorentino, Italy;‎ Univ Firenze, Dipartimento Fis & Astron, Sesto Fiorentino, Italy;‎ CNR, INO, Sesto Fiorentino, Italy

Abstract: Ferromagnetism is a pure quantum correlation phenomenon, and yet it is responsible for most magnetic phenomena that we encounter in everyday life. Metallic magnets, such as iron and nickel, owe their magnetic behavior to mobile conduction electrons, whose spins can align with one another giving rise to non-zero magnetization. In the 1930s, Edmund C. Stoner first devised a simple and minimal model, where a ferromagnetic instability of the homogeneous Fermi gas is afforded only through short-range repulsive interactions. While his model captures the fundamental physics behind itinerant ferromagnetism, various additional effects in solid materials, such as orbital couplings and peculiar band dispersions, make it difficult to isolate the Stoner mechanism. Here we present our experimental investigation performed on an ultracold Fermi mixture of Li-6 atoms where only genuine short-range repulsive interactions are present. Studying the stability of an artificially created ferromagnetic state, we provide a signature of a Stoner-like instability in a metastable system.


Volume: 40 (2)      Pages from: 91-1  to: 91-5

KeyWords: Ferromagnetism; Fermi gas
DOI: 10.1393/ncc/i2017-17091-8

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