Searching for New Spin-Dependent Interactions with SmCo$_5$ Spin Sources and a SERF Comagnetometer

TL;DR

This paper introduces a new experimental approach combining SmCo$_5$ spin sources and a SERF comagnetometer to significantly improve the sensitivity in detecting potential new spin- and velocity-dependent forces at macro scales.

Contribution

It presents a novel method using iron-shielded SmCo$_5$ and SERF technology to enhance detection sensitivity for SVDFs, surpassing previous experimental limits.

Findings

Potential to improve sensitivity by over 10 orders of magnitude.

Feasibility of creating high spin density sources with iron shielding.

Proposed method can explore force ranges larger than 1 cm.

Abstract

We propose a novel method to search for possible new macro-scale spin- and/or velocity-dependent forces (SVDFs) based on specially designed SmCo$_5$ spin sources and a spin exchange relaxation-free (SERF) comagnetometer. A simulation shows that, by covering a SmCo$_5$ permanent magnet with a layer of pure iron, a high net spin density source of about $1\times 10^{22}$/cm$^3$ could be obtained. Taking advantages of the high spin density of this iron-shielded SmCo$_5$ and the high sensitivity of the SERF, the proposed method could set up new limits of greater than 10 orders of magnitude more sensitive than those from previous experiments or proposals in exploring SVDFs in force ranges larger than 1 cm.