Metamagnetism

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

Phenomenological Mean-Field Theory of Metamagnetism in Heavy Fermion Compounds under Constant Pressure Conditions with Application to CeRu2Si2

Abstract: To understand metamagnetism in specific heavy fermion compounds, we explored the phenomenological mean-field theory with magnetic interaction by using the heavy fermion characteristic temperature Tm without a microscopic mechanism. We describe an extension of the Landau-like free energy density with Bragg–Williams entropy. By minimizing this free energy density with respect to the magnetization, we obtained thermal equilibrium quantities in theoretical terms. For the heavy fermion system with the large Grüneisen parameter, we used the scaling hypothesis to take account of the volume dependence in the experimental data under constant pressure conditions. As an example, the magnetic behaviors of the CeRu2Si2 with a paramagnetic ground state is examined and explained in qualitative terms.

Ultra-sharp metamagnetic transitions in the half-doped

Abstract: Magnetization, electrical-resistance and specific-heat measurements have been performed on the ABO3-type half-doped Eu0.5Sr0.5MnO3 manganite compound. These studies reveal successive sharp step-like metamagnetic transitions at low temperatures. The steps are sharp at T ≤ 3 K but smeared above 3 K, signifying the transformation from a homogenous to an inhomogenous phase-separated state at 3 K. Earlier such successive sharp steps have been observed mostly in Pr-based manganites (in which Pr is magnetic). The observation of the similar steps in the present Eu-based system (in which Eu is non-magnetic), along with the irreversibility in the magnetization isotherms, suggests that rare-earth magnetism has no role in the occurrence of this fascinating property. The temperature- and magnetic-field-dependent phase transitions in ABO3-type half- doped manganites have attracted considerable attention in the recent few years. The elec- tronic and magnetic properties of such R0.5A0.5MnO3 (R = rare-earth, A = divalent cation) systems are influenced by various spin, charge and orbitals correlations. These correlations are highly sensitive to the tolerance factor (which decides the eg electron bandwidth), cation size mismatch at A-site, and dilution of Mn-site by impurity doping (1-11). Depending upon these factors, CE-type half-doped compounds, such as La0.5Ca0.5MnO3 ,N d 0.5Sr0.5MnO3, Pr0.5Sr0.5MnO3, exhibit various electronic and magnetic transitions, such as transformation from ferromagnetic (FM) metallic to charge-ordered (CO) antiferromagnetic (AFM) state as a function of temperature, and magnetic-field-induced melting of CO AFM state to FM metal- lic state (3-6). The experimental observations of the first-order transitions of CE-type AFM phase to FM phase have been supported by theoretical studies which have also emphasized that the CE phase is fragile to disorder (12, 13). Metamagnetism is another property observed in low-bandwidth hole-doped and half-doped Pr-based systems exhibiting CO state. At low temperatures, these Pr-based systems exhibit sharp step-like metamagnetic transitions, which smear to broader transitions at high temper- atures (8-11, 14-17). Such transitions are induced by a field-sensitive phase separation that