Metamagnetism

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

Stress-induced transformations at low temperatures in a Ni45Co5Mn36In14 metamagnetic shape memory alloy

Abstract: The martensitic transformation behavior in a Ni45Co5Mn36In14 was investigated at low temperatures. Almost perfect superelasticity was confirmed below 200 K. The reverse transformation finishing stress monotonically decreased with decreasing temperature and the forward transformation starting stress changed from a decrease to an increase at ∼125 K. The temperature dependence of equilibrium stress had the same tendency as that of equilibrium magnetic field, allowing the thermal transformation arrest temperature to be determined. The temperature dependence of hysteresis in stress-induced transformation was also similar to that in magnetic-field-induced transformation, and the levels of dissipation energy yielded by the stress and magnetic field were intrinsically equivalent.

Evidence of large magneto-dielectric effect coupled to a metamagnetic transition in Yb2CoMnO6

Abstract: The double perovskite Yb2CoMnO6 has been synthesized with an almost perfect checkerboard arrangement of Co2+ and Mn4+ cations in the B-sublattice of the perovskite cell. It presents an anomaly in the electric capacitance and a strong magneto-dielectric effect at about 40 K whose interplay with the microscopic magnetic behavior has been investigated by means of neutron diffraction, magnetization, pyroelectric, and relative dielectric permittivity measurements. We show that the onset of an E-type antiferromagnetic ordering of Co2+ and Mn4+ moments monitored by neutron diffraction provokes the noticeable jump of the relative dielectric permittivity (∼9%) at about 40 K. It is also shown that this jump can be totally suppressed by application of a magnetic field of μ0H = 5 T. Neutron experiments and magnetic measurements confirm that such a suppression leading to a significant magneto-dielectric effect is driven by a metamagnetic phase transition from the peculiar E-type ordering of 3d moments into a collinear...

Magnetization behavior and magnetic entropy change of frustrated Ising antiferromagnets on two- and three-dimensional lattices

Abstract: The magnetization behavior and the magnetic entropy change of frustrated Ising antiferromagnets with spin-1/2 on two-dimensional triangular and three-dimensional hexagonal closed-packed lattices are calculated by using Monte Carlo simulation. The results indicate that the normalized magnetization as a function of external field shows a 1/3 plateau on the two-dimensional system, while it shows 0 and 1/2 plateaus on the three-dimensional system at low temperature. Consequently, it causes an inverse magnetocaloric effect, namely, the value of magnetic entropy change may be positive in some ranges of magnetic fields. This phenomenon may be used to cool in a field by adiabatic demagnetization. Moreover, we analyze the spin configurations of systems on the magnetization plateaus, and discuss the impact of the frustration. We also find a mapping of the magnetization plateaus to the magnetic entropy changes at low temperature. The study of such systems showing field-induced metamagnetic transition in relation to frustrated antiferromagnets may open an important field in searching for good candidates for room-temperature magnetic refrigeration.

Itinerant electron metamagnetism and a large decrease in the electronic specific heat coefficient of Laves-phase compounds Lu(Co1-xGax)2

Abstract: High-field magnetization and low-temperature specific heat of the nearly ferromagnetic compounds Lu(Co1-xGax)2 have been investigated. A sharp metamagnetic transition has been observed in these compounds. The critical field Hc decreases with increasing x and becomes lower than 1 T at x=0.12. However, no spontaneous magnetization is confirmed even above x=0.15. With increasing x, the electronic specific heat coefficient gamma increases and reaches 36 mJ K-2 mol-1 for x=0.12 in 0 T, being 1.5 times as large as that of LuCo2. Such a mass enhancement is discussed in terms of the spin fluctuation. The gamma value of the ferromagnetic state for the specimen with x=0.12 in a magnetic field of 14.6 T is reduced about 50% compared with that of the paramagnetic state in zero field. This means that the metamagnetic transition results in a drastic reduction of the spin fluctuation in the compound.

Magnetic behavior of poly(3-methylthiophene): Metamagnetism and room-temperature weak ferromagnetism

Abstract: A weak ferromagnetic phase is shown in pressed pellets of partially doped poly~3-methylthiophene !~ P3MT! in the whole range from 1.8 to 300 K in magnetic measurements. Thermoremanence data have been used to estimate the suppression of this phase to be around 815 K. We also show that instead of the classical antiferromagnetism for the first-order interaction that gives weak ferromagnetism as a second-order effect, metamagnetic behavior is observed. X-band electron spin resonance ~ESR! measurements and magnetization measurements allowed us to estimate that 8.1% of the total number of spins contributes to the weak ferromagnetism at room temperature. The doping level obtained from the ESR data is in good agreement with that estimated from electron dispersive spectroscopy measurements.