Metamagnetism

About: Metamagnetism is a research topic. Over the lifetime, 2023 publications have been published within this topic receiving 38108 citations.

Magnetic properties and magnetic entropy change of LaFe11.5Si1.5Hy interstitial compounds

Abstract: LaFe11.5Si1.5Hy interstitial compounds have been prepared by hydrogen absorption and subsequent desorption. The Curie temperatures are easily tunable for a wide temperature range from ~ 195 to ~ 340 K by hydrogen content. The maximal magnetic entropy changes, under a magnetic field change of 0?5 T, are as large as 16.8? 20.5 J kg?1 K?1, exceeding that of Gd (|?S| ~ 9.8 J kg?1 K?1 at TC = 293 K) by 70?110% in the vicinity of room temperature. The large magnetic entropy change of all hydrides may be attributed to the first-order itinerant-electron metamagnetic transition confirmed by the Arrott plots. Large |?S|, convenient adjustment of TC and small thermal and magnetic hystereses, make LaFe11.5Si1.5Hy interstitial hydrides promising candidates for magnetic refrigerants in the corresponding temperature range.

Magnetic properties, electrical resistivity and thermal expansion of (Ho,Y)Co2

Abstract: The influence of the Ho substitution on the Co moments in (HoxY1-x)Co2 has been investigated by means of magnetic, resistivity and lattice parameter measurements. A first-order phase transition and a field-induced metamagnetism can be detected for x>or=0.7. At the magnetic transition temperature anomalies of the lattice parameters were measured for x>or=0.3. In connection with the first-order transition a discontinuity in the rho (T) curves appears for x>or=0.7. For 0.3 150K) the rho (T) curves show a tendency to saturation, which is the same for all x values. Considering the substitution of Ho into YCo2 the existence of a critical RE concentration (x>0.1) for the appearance of a long-range magnetic order is evidenced. The Co moments mu Co are compared with neutron diffraction results. The overall agreement is very good and supports the assumption of induced Co moments. For the whole pseudobinary system, a Fermi energy situated in a steep flank of the density of states function was assumed.

Metamagnetic phase transition of the antiferromagnetic Heisenberg icosahedron.

Abstract: The observation of hysteresis effects in single molecule magnets like Mn12-acetate has initiated ideas of future applications in storage technology. The appearance of a hysteresis loop in such compounds is an outcome of their magnetic anisotropy. In this Letter we report that magnetic hysteresis occurs in a spin system without any anisotropy, specifically where spins mounted on the vertices of an icosahedron are coupled by antiferromagnetic isotropic nearest-neighbor Heisenberg interaction giving rise to geometric frustration. At T = 0 this system undergoes a first-order metamagnetic phase transition at a critical field Bc between two distinct families of ground state configurations. The metastable phase of the system is characterized by a temperature and field dependent survival probability distribution.

Solution synthesis of gadolinium nanoparticles.

Abstract: Gadolinium nanoparticles have been produced at subambient temperature by alkalide reduction. The nanoparticles display maxima in the temperature dependence of their magnetization, cooled in the absence of an applied external field, at Tmax of 5.0 and 17.5 K for unheated samples and samples annealed at 1000 °C for 4 h, respectively. Field cooled behavior deviates at temperatures slightly above Tmax, increasing at lower temperature. Curie−Weiss law fits of the high-temperature data yield magnetic moments in close agreement with those expected for noninteracting Gd3+ ions, suggesting that the behavior seen is due to a magnetic transition rather than superparamagnetism. Magnetization is linearly dependent on field at temperatures higher than 7−8 times Tmax and shows remanence-free hysteresis at lower temperature, suggesting metamagnetism. Some annealed samples show evidence of additional ferromagnetic interactions below ∼170 K. Magnetic entropy curves generated from magnetization data are consistent with that...