1,721,020 research outputs found
Nanostructure-driven complex magnetic behavior of Sm2CoMnO6 double perovskite
Full text linkMagnetic double perovskite oxides have steadily emerged as an important class of functional materials. A clear understanding of the complex interactions that govern the magnetic behavior, and thereby, the functionality in these mixed valence compounds, however, remains elusive. In this study, we show that the complex nanostructure that forms in these compounds is at the root of their magnetic behavior. Using complementary experimental and micromagnetic simulation results, we have uncovered the complex nanostructure of polycrystalline Sm2CoMnO6, a typical double perovskite oxide, and established how the nanostructure drives its magnetic behavior. Our results show that Sm2CoMnO6 exhibits a Griffiths phase with the formation of ferromagnetic clusters above the ordering temperature. The isothermal magnetization curves show no sign of saturation, even at the highest measured field (9 T), and irreversibility in the entire magnetic field range. Despite a very clear indication of the presence of antiferromagnetic antisite defects, surprisingly, no antisite defect-induced exchange bias occurs. This is explained from the micro magnetic simulations that confirm the presence of ferromagnetic nanoclusters and nanosized, random, and uncorrelated antisite defects, resulting in no exchange bias. This work provides a clear understanding of the role of antisite defects, in particular, on how their structure can lead to the presence/absence of exchange bias. The fundamental insight offered in this work fills an important knowledge gap in the field and will be of immense value in realizing the true potential of double perovskite oxides for future technological applications. (C)& nbsp;2022 The Author(s). Published by Elsevier B.V
Advances in Magnetic Nanomaterials and Nanostructures
Full text linkMagnetic nanomaterials, in which non-bulk magnetic properties emerge because of their low dimension, are a class of materials with huge application potential in several areas, providing, at the same time, an exciting field of fundamental research [...
Investigation of the ferromagnetic order in a crystalline Fe2Zr alloy
No full textWe present the study of the ferromagnetic behaviour of a crystalline Fe2Zr sample obtained by arc melting.
Mossbauer spectroscopy measurements show that the sample is magnetically ordered at room temperature with
ferromagnetic order. The magnetization behaviour obtained by superconducting quantum interference device
magnetometry measurements indicates that the sample is a soft ferromagnet
Magnetic Properties and Electronic Structures of Compounds from Hf-Co Phase System
No full textMagnetic measurements of molar susceptibilities as a function of temperature in the temperature
range between 5 and 400 K were performed for the intermetallic compounds Hf2Co and HfCo2,
using a SQUID magnetometer. The density of states at the Fermi level for Hf2Co was evaluated
from the measured spin paramagnetic susceptibility. In addition, band structure calculations using
the augmented plane waves plus local orbitals (APW+lo) method as implemented in the WIEN2k
programme package for the two compounds were done. The obtained results were compared with the
measured data
Studio di sistemi di eccitazione per laser a CO2 di potenza a scarica elettrica in corrente alternata
No full text
Charge-Ordering and Magnetic Transitions in Nanocrystalline Half-Doped Rare Earth Manganite Ho0.5Ca0.5MnO3
Full text linkThis work investigates nanostructured Ho0.5Ca0.5MnO3, considered a model system of the Ln0.5Ca0.5MnO3 series of manganites with perovskite structures featuring small lanthanide (Ln) ions half-substituted by Ca ions. Here, we propose a modified hybrid sol–gel–solid-state approach to produce multiple samples with a single batch, obtaining very high crystalline quality and ensuring the same chemical composition, with an average particle size in the range 39–135 nm modulated on-demand by a controlled calcination process. Our findings evidence that, provided the crystalline structure is preserved, the charge-ordering transition can be observed even at the nanoscale. Additionally, this research explores the presence of glassy phenomena, which are commonly seen in this class of materials, to enhance our understanding beyond simplistic qualitative observations. Comprehensive characterization using DC and AC magnetometry, along with relaxation and aging measurements, reveals that the complex dynamics typical of glassy phenomena emerge only at the nanoscale and are not visible in the bulk counterpart. Nevertheless, the analysis confirms that even the sample with the smallest nanoparticles cannot be intrinsically classified as canonical spin glass
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