High-resolution neutron depolarization microscopy of the ferromagnetic transitions inNi3Al and HgCr2Se4 under pressure

Published

April 21, 2021

Author(s)

Daniel S. Hussey, Muhammad Abir, B. Khaykovich, C. Pfleiderer, Pau Jorba, Marc Seifert, Michael Schulz

Abstract

We performed spatially resolved imaging of ferromagnetic transitions in Ni3Al and HgCr2Se4 crystals. These neutron depolarization measurements discovered bulk magnetic inhomogeneities in the ferromagnetic transition temperature with the spatial resolution about 100 m. To obtain such spatial resolution, we employed a novel neutron microscope equipped with Wolter mirrors as a neutron image-forming lens and a focusing neutron guide as a neutron condenser lens. The images of Ni3Al show that the sample does not homogeneously go through the ferromagnetic transition. The improved resolution allowed us to identify a distribution of small grains with slightly o -stoichiometric composition. Additionally, neutron depolarization imaging experiments on the chrome spinel, HgCr2Se4, under high pressures up to 15 kbar highlight the advantages of the new technique especially for small samples or sample environments with restricted sample space. The improved spatial resolution enables to observe domain formation in the sample while decreasing the acquisition time despite having a bulky pressure cell in the beam. The novel optical design that enabled acquisition of the high spatial resolution neutron depolarization images is described in detail and image results are compared to a conventional radiography setup without a lens.

Citation

Physical Review B

Pub Type

Journals

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Keywords

quantum phase transition, wolter optics, neutron polarization imaging

Citation

, D. , Abir, M. , Khaykovich, B. , Pfleiderer, C. , Jorba, P. , Seifert, M. and Schulz, M. (2021), High-resolution neutron depolarization microscopy of the ferromagnetic transitions inNi3Al and HgCr2Se4 under pressure, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925285 (Accessed September 7, 2024)