Metamagnetism

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

Synthesis, structure and magnetic properties of Pr0.65Ca0.3M0.05MnO3 (M = Na, K and Ag): A perovskite manganites with metamagnetic phase transitions

Abstract: The synthesis, structural characterization, and magnetic properties of Pr0.65Ca0.3M0.05MnO3 (M = Na, K and Ag) perovskite manganites are reported. Our samples were synthesized using the solid state reaction method at high temperature. Rietveld refinements of the X-ray diffraction patterns show that all our samples are single phase and crystallize in the distorted orthorhombic system with Pbnm space group. The surface morphology and infrared absorption of the samples were systematically investigated. Magnetization measurements versus temperature in a magnetic applied field of 50 mT showed that the antiferromagnetic ordering temperature TAFM occurring below the charge-ordering transition temperature TCO in these narrow band manganites are slightly dependent with monovalent element. The critical magnetic field (Hc) required for metamagnetism is found to reduce drastically from 7 T for Pr0.65Ca0.35MnO3 to 2.9 T for Pr0.65Ca0.3Na0.05MnO3.

Effects of Fe doping on magnetic and transport properties in Pr0.75Na0.25MnO3

Abstract: Single-phase polycrystalline perovskites Pr 0.75 Na 0.25 Mn 1―x Fe x O 3 (0 ≤ x ≤ 0.30) were prepared by a sol―gel technique, which can reduce the volatilization of Na, and avoid the precipitation of manganese oxide. The effects of Fe doping at the Mn site upon the charge and the magnetic order in Pr 0.75 Na 0.25 MnO 3 have been investigated combining magnetic and transport properties measurements. The results show that for low temperatures long range charge order (CO) is weakened even at doping concentration as low as 2%. The ferromagnetic (FM) fraction increases with increase in the Fe doping for x ≤ 5%, and decreases by further Fe doping. This complex behavior is interpreted in terms of the competition between geometric effect (size of the dopant) and the effect of electronic configuration of the dopant. The steplike metamagnetic transition for the x ≤ 5% samples is observed and the origin is ascribed to the phase transition from CO antiferromagnetic (AFM) phase to FM phase in a phase separation scenario.

Ferromagnetic quantum criticality in the uranium-based ternary compounds URhSi, URhAl, and UCoAl

Abstract: In this thesis we explore the ferromagnetic quantum criticality in three uranium-based ternary compounds, by means of thermodynamical and transport measurements on single crystal samples, at low temperature and high pressure. URhSi and URhAl are itinerant ferromagnets, while UCoAl is a paramagnet being close to a ferromagnetic instability. All of them have Ising-type magnetic ordering. In the orthorhombic compound URhSi, we show that the Curie temperature decreases upon applying a magnetic field perpendicular to the easy magnetization axis, and a quantum phase transition is expected around 40~T. In the hexagonal system URhAl, we establish the pressure--temperature phase diagram for the first time, indicating a quantum phase transition around 5~GPa. In the isostructural compound UCoAl, we investigate the metamagnetic transition with measurements of magnetization, Hall effect, resistivity and X-ray magnetic circular dichroism. Some intriguing magnetic relaxation phenomena are observed, with step-like features. Hall effect and resistivity have been measured at dilution temperatures, under hydrostatic pressure up to 2.2 GPa and magnetic field up to 16~T. The metamagnetic transition terminates under pressure and magnetic field at a quantum critical endpoint. In this region, a strong effective mass enhancement occurs, and an intriguing difference between up and down field sweeps appears in transverse resistivity. This may be the signature of a new phase, supposedly linked to the relaxation phenomena observed in magnetic measurements, arising from frustration on the quasi-Kagome lattice of uranium atoms in this crystal structure.