Magnetic Resonance in Gadolinium Nanoparticles near the Curie Point

• Published in: Technical physics Vol. 63; no. 4; pp. 519 - 529
• Main Authors: Petinov, V. I., Dremov, V. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-04-2018; Springer; Springer Nature B.V
• Subjects: Classical and Continuum Physics; COERCIVE FORCE; Coercivity; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CURIE POINT; Curie temperature; ELECTRON SPIN RESONANCE; FERROMAGNETIC RESONANCE; GADOLINIUM; HYSTERESIS; LANDE FACTOR; LINE WIDTHS; Magnetic properties; Magnetic resonance; MAGNETIZATION; Magnetization reversal; NANOPARTICLES; NANOSCIENCE AND NANOTECHNOLOGY; PARAMAGNETISM; Physics; Physics and Astronomy; Rare earth metal compounds; Solid State; SPECTRA; SPHERICAL CONFIGURATION; TEMPERATURE DEPENDENCE
• ISSN: 1063-7842; 1090-6525
• DOI: 10.1134/S1063784218040175

The Influence of temperature in the range from 275 to 320 K on ESR spectra and magnetization m of ensembles of spherical gadolinium nanoparticles with the diameter from 89 to 18 nm was studied. The particles with
d
= 18 nm had a cubic face centered structure and no magnetic transition. At
T
>
T
C
all particles were paramagnetic, and their g factors were
g
= 1.98 ± 0.02 irrespective of their size and structure. At
T
=
T
C
the particles having 28 to 89 nm in size experienced a magnetic and orientation transition; at
T
<
T
C
their
m
(
H
) dependences were described by the Langevin function, and the FMR lines broadened and shifted towards
H
= 0. FMR lines of the Gd particle ensembles showed a hysteresis behavior during magnetization reversal, which did not correlate with the coercivity of the particles. Dependences of the Gd nanoparticles FMR linewidth Δ
H
(
T
) changed proportionally to |
T
–
T
C
|.