Local manipulation of quantum magnetism in 1D ultracold Fermi gases across narrow resonances

TL;DR

This paper demonstrates how the effective range in two-body scattering can significantly influence quantum magnetism in 1D ultracold Fermi gases, enabling local control of magnetic phases through narrow resonances.

Contribution

It reveals the role of effective range in breaking spin degeneracy and inducing density-sensitive exchange interactions, offering new ways to manipulate quantum magnetism locally.

Findings

Effective range modifies magnetic properties in 1D Fermi gases.

Coexistence of AFM and FM correlations in a harmonic trap.

Proposed detection method via tunneling experiments.

Abstract

Effective range is a quantity to characterize the energy dependence in two-body scattering strength, and is widely used in cold atomic systems especially across narrow resonances. Here we show that the effective range can significantly modify the magnetic property of one-dimensional (1D) spin-$1/2$ fermions in the strongly repulsive regime. In particular, the effective range breaks the large spin degeneracy in the hard-core limit, and induces a Heisenberg exchange term in the spin chain that is much more sensitive to the local density than that induced by the bare coupling. With an external harmonic trap, this leads to a very rich magnetic pattern where the anti-ferromagnetic (AFM) and ferromagnetic (FM) correlations can coexist and distribute in highly tunable regions across the trap. Finally, we propose to detect the range-induced magnetic order in the tunneling experiment. Our results can be directly tested in 1D Fermi gases across narrow resonance, and suggest a convenient route towards the local manipulation of quantum magnetism in cold atoms.