Ferromagnetic response of thin NiI$_2$ flakes up to room temperatures

Fuente: arXiv
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Main Authors: Orlova, N. N., Avakyants, A. A., Timonina, A. V., Kolesnikov, N. N., Deviatov, E. V.
Format: Preprint
Published: 2023
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author Orlova, N. N.
Avakyants, A. A.
Timonina, A. V.
Kolesnikov, N. N.
Deviatov, E. V.
author_facet Orlova, N. N.
Avakyants, A. A.
Timonina, A. V.
Kolesnikov, N. N.
Deviatov, E. V.
contents We investigate the magnetic response of thin NiI$_2$ flakes for temperatures above 80~K. Since no magnetic ordering is expected for bulk NiI$_2$, we observe clear paramagnetic response for massive NiI$_2$ single crystals. In contrast, thin NiI$_2$ flakes show well-defined ferromagnetic hysteresis loop within $\pm2$~kOe field range. The value of the response does not scale with the sample mass, ferromagnetic hysteresis can be seen for any flake orientation in the external field, so it originates from the sample surface, possibly, due to the anisotropic exchange (Kitaev interaction). The observed ferromagnetism is weakly sensitive to temperature up to 300~K. If a flake is multiply exposed to air, ferromagnetic hysteresis is accompanied by the periodic modulation of the magnetization curves, which is usually a fingerprint of the multiferroic state. While NiI$_2$ flakes can not be considered as multiferroics above 80~K, surface degradation due to the crystallohydrate formation decreases the symmetry of NiI$_2$ surface, which produces the surface ferroelectric polarization in addition to the described above ferromagnetic one.
format Preprint
id arxiv_https___arxiv_org_abs_2309_08392
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Ferromagnetic response of thin NiI$_2$ flakes up to room temperatures
Orlova, N. N.
Avakyants, A. A.
Timonina, A. V.
Kolesnikov, N. N.
Deviatov, E. V.
Mesoscale and Nanoscale Physics
We investigate the magnetic response of thin NiI$_2$ flakes for temperatures above 80~K. Since no magnetic ordering is expected for bulk NiI$_2$, we observe clear paramagnetic response for massive NiI$_2$ single crystals. In contrast, thin NiI$_2$ flakes show well-defined ferromagnetic hysteresis loop within $\pm2$~kOe field range. The value of the response does not scale with the sample mass, ferromagnetic hysteresis can be seen for any flake orientation in the external field, so it originates from the sample surface, possibly, due to the anisotropic exchange (Kitaev interaction). The observed ferromagnetism is weakly sensitive to temperature up to 300~K. If a flake is multiply exposed to air, ferromagnetic hysteresis is accompanied by the periodic modulation of the magnetization curves, which is usually a fingerprint of the multiferroic state. While NiI$_2$ flakes can not be considered as multiferroics above 80~K, surface degradation due to the crystallohydrate formation decreases the symmetry of NiI$_2$ surface, which produces the surface ferroelectric polarization in addition to the described above ferromagnetic one.
title Ferromagnetic response of thin NiI$_2$ flakes up to room temperatures
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2309.08392