Metamagnetism

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

Low-temperature properties of YbRh2Si2

Abstract: Stoichiometric YbRh2Si2 single crystals (ThCr2Si2 structure) are studied by means of magnetic susceptibility χ=M/B, electrical resistivity ρ, and specific heat C measurements. High temperature χ(T) follows a Curie–Weiss law with effective magnetic moments close to the value of free Yb3+. At low temperatures χ is highly anisotropic: due to strong single-ion effects χa along the basal plane of the tetragonal structure is up to 20 times larger than χc along the c-axis direction. No evidence of either magnetic order at low fields or metamagnetism up to B∼10 T is observed in χ down to 2K. ρ(T) is almost temperature independent above 100 K but shows a rapid, continuous drop as T decreases. Below T K both ρ and C show deviations from the Fermi liquid properties ρ(T)∝T2 and C/T=γ=constant, which are typical for compounds close to a magnetic instability.

Phase transitions induced by magnetic field in ferrimagnets with one unstable magnetic subsystem

Abstract: Within the molecular field theory, magnetic phase diagrams for a two-sublattice ferrimagnet with one unstable magnetic subsystem are determined. A detailed analysis is given for the experimental magnetization curve for the f-d ferrimagnet Yo.75Tmo.25(Coo.ssAlo.12)2 measured up to 38 T at 4.2 K in which two metamagnetic transitions and a non-collinear phase between them are observed. If any of the magnetic subsystems of a ferrimagnet exhibits a magnetic instability, i.e. a metamagnetic transition from a weakly (with magnetization Mw) to a strongly (Ms) magnetic state, a magnetic field can induce a sequence of magnetic phase transitions which differ in their nature (transitions between collinear and non-collinear structures as well as a metamagnetic transition). In the exchange approximation within the molecular field theory, we calculated various possible magnetic phase sequences for a two-sublattice ferrimagnet of this type. In view of the basic proposition of molecular field theory that in the thermodynamic equilibrium state the sublattice magnetizations are aligned along the effective fields acting on them, we construct phase diagrams by analyzing the values and signs of these effective fields. Possible phase diagrams depend on the parameters of the system: the exchange parameter 2, the metamagnetic transition field H m and the sublattice magnetic moments MI and M 2.

Metamagnetism in CePd5Ge3.

Abstract: Metamagnetic transitions in CePd5Ge3 were investigated by means of low-temperature magnetization, magnetic susceptibility, electrical resistivity and magnetoresistivity measurements. In transverse magnetic fields applied in a direction close to the b-axis the antiferromagnetic structure of the compound undergoes two successive transitions, first to a spin-flop phase and then to a paramagnetic phase with field-induced ferromagnetic-like alignment of the Ce magnetic moments. In contrast, a single anomaly occurs in the magnetic field dependences of the resistivity in a transverse magnetic field applied close to the c-axis, which reflects a direct transition from antiferromagnetic to paramagnetic state. Such behavior is in agreement with theoretical descriptions of metamagnetic transitions in uniaxial antiferromagnets. The experimental magnetic and electrical transport data indicate that the b-axis is the easy axis of magnetization in CePd5Ge3.

H–T magnetic phase diagrams of electron-doped Sm1−xCaxMnO3

Abstract: The magnetic properties of the polycrystalline electron-doped manganites Sm1−xCaxMnO3 have been studied for 1⩾x⩾0.67 under high magnetic fields up to 50 T. H–T phase diagrams have been established. Doping the G-type AFM parent compound CaMnO3 leads to partial FM correlations superimposed on a AFM component. The former phenomena reaches its maximum strength for x=0.88–0.9. For x=0.8 and below, abrupt metamagnetic transitions occur from the AFM ground state to the FM state with large hysteresis between the first magnetization and remanence curves. This phenomena corresponds to the melting of the orbital- or charge-ordered phases. At intermediate concentrations close to x=0.85, the magnetization curves exhibit first a FM component and then a metamagnetic transition, so that this behavior can thus be viewed as a sum of the two types of previous behaviors, clearly showing the occurrence of phase separation.