Temperature-variable apparatus for measuring Barnett field

Maki Umeda; Hiroyuki Chudo; Masaki Imai; Nana Sato; Eiji Saitoh

doi:10.1063/5.0142318

Temperature-variable apparatus for measuring Barnett field

Rev Sci Instrum. 2023 Jun 1;94(6):063906. doi: 10.1063/5.0142318.

Authors

Maki Umeda¹, Hiroyuki Chudo¹, Masaki Imai¹, Nana Sato¹, Eiji Saitoh^{1

2

3

4}

Affiliations

¹ Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
² Department of Applied Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
³ Institute for AI and Beyond, The University of Tokyo, Tokyo 113-8656, Japan.
⁴ Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.

PMID: 37862522
DOI: 10.1063/5.0142318

Abstract

We have developed experimental equipment for observing the Barnett effect, in which mechanical rotation magnetizes an object, at low temperatures. A sample in a rotor is rotated bidirectionally using a temperature-controlled high-pressure gas. The stray field generated from the sample due to the Barnett effect was detected using a fluxgate magnetic sensor with a sensitivity on the order of several picoteslas, even at low temperatures. By replacing the rotor with a solenoid coil, the magnetic susceptibility of the sample was estimated from the stray field to be of the same order of magnitude as that due to the Barnett effect. The Barnett field was estimated using the dipole model. To assess the performance of the setup at low temperatures, measurements were performed on commercial magnetite (Fe3O4) nanogranules. We confirmed the accordance of the g' factor between the experimental results using the present setup and those of our previous study performed at room temperature.