High-resolution neutron depolarization microscopy of the ferromagnetic transitions in Ni3Al and HgCr2Se4 under pressure

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:475

Article

Jorba, Pau¹  Schulz, Michael²  Hussey, Daniel S.³  Abir, Muhammad⁴  Seifert, Marc^1,2  Tsurkan, Vladimir^5,6  Loidl, Alois⁵  Pfleiderer, Christian¹  Khaykovich, Boris⁴ 

[1] Tech Univ Munich, Phys Dept, D-85748 Garching, Germany

[2] Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, D-85748 Garching, Germany

[3] NIST, Phys Measurement Lab, 100 Bur Dr,MS 8461, Gaithersburg, MD 20899 USA

[4] MIT, Nucl Reactor Lab, 77 Massachusetts Ave, Cambridge, MA USA

[5] Univ Augsburg, Expt Phys 5, Ctr Elect Correlat & Magnetism, D-86159 Augsburg, Germany

[6] Inst Appl Phys, Kishinev, Moldova

关键词: Neutron imaging;    Crystal growth;    Pressure techniques;    Magnetic domains;    Magnetic phase transitions;    Quantum phase transitions;   

DOI  :  10.1016/j.jmmm.2018.11.086

来源: Elsevier

【 摘 要 】

We performed neutron imaging of ferromagnetic transitions in Ni3Al and HgCr2Se4 crystals. These neutron depolarization measurements revealed bulk magnetic inhomogeneities in the ferromagnetic transition temperature with spatial resolution of about 100 mu 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 off-stoichiometric composition. Additionally, neutron depolarization imaging experiments on the chrome spinel, HgCr2Se4, under 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 one to observe domain formation in the sample while decreasing the acquisition time despite having a bulky pressure cell in the beam.

【 授权许可】

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