Metamagnetism

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

Magnetic Phase Transitions in Low-Dimensional Systems

Abstract: Phase transitions are of current interest in many areas of condensed matter physics They occur in many systems, among them we can mention liquid-gas transition, superfluidity, binary alloys (such as β-brass), structural phase transitions and magnetic phase transitions (MPT) The MPT are especially interesting because of the wide variety of available magnetic compounds with different lattices, spins and interactions The simplest case of an MPT is the ferromagnetic transition which is usually of second order and only occurs in zero magnetic field The case of two sublattices antiferromagnets is richer since they undergo phase transitions in a certain range of applied magnetic fields, which can be of first order (metamagnetism; spin-flop phases) Besides these simple ferromagnets and antiferromagnets (F and AF), other magnetic compounds which exhibit a more complex class of phase transitions are found such as: systems with a non magnetic ground state induced either by zero field splitting, or in the case of magnetic chains, by alternating AF interactions; magnetic chains with a large magnetoelastic coupling inducing a spin-Peierls transition; frustrated antiferromagnets with more than two sublattices or with incommensurate magnetic ordering

Magnetic properties of a new intermetallic compound Ho2Ni2Pb

Abstract: Single-phase, textured samples of a new orthorhombic intermetallic compound Ho2Ni2Pb have been fabricated (space group Cmmm). Here the bulk magnetic properties are presented as determined via magnetization, susceptibility, heat capacity and resistivity measurements. The results exhibit two distinct magnetic transitions and large metamagnetic effects. Such behaviour is related to the unusual rare-earth symmetry of the highly anisotropic crystal structure.

Ground-state magnetic phase diagram of bow-tie graphene nanoflakes in external magnetic field

Abstract: The magnetic phase diagram of a ground state is studied theoretically for graphene nanoflakes of bow-tie shape and various sizes in external in-plane magnetic field. The tight-binding Hamiltonian supplemented with Hubbard term is used to model the electronic structure of the systems in question. The existence of the antiferromagnetic phase with magnetic moments localized at the sides of the bow-tie is found for low field and a field-induced spin-flip transition to ferromagnetic state is predicted to occur in charge-undoped structures. For small nanoflake doped with a single charge carrier, the low-field phase is ferrimagnetic and a metamagnetic transition to ferromagnetic ordering can be forced by the field. The critical field is found to decrease with increasing size of the nanoflake. The influence of diagonal and off-diagonal disorder on the mentioned magnetic properties is studied. The effect of off-diagonal disorder is found to be more important than that of diagonal disorder, leading to significantly widened distribution of critical fields for disordered population of nanoflakes.

Electronic structure of the uranium-3d transition metal laves phases

Abstract: Electronic structure calculations within the linearized muffin-tin orbital (LMTO) method have been performed for the uranium-3d metal Laves phases. Calculated equilibrium volumes show very good agreement with experimental data. The spin-only magnetic properties of UFe2 were also considered and the calculated Fe spin moment agrees quite well with measurements. It is noteworthy that the uranium 5f spin moment is found to be antiparallel to the iron moment. The spin magnetism of UFe2 was also calculated as a function of pressure. The 3d spin moment is found to initially decrease by 1.5 μB/Mbar. Around 500 kbar the magnetism is calculated to disappear. For UCo2 a paramagnetic ground state was obtained, which, however, in agreement with data, is enhanced quite substantially. Finally, for UMn2 the Stoner criterion for magnetism was found to be just fulfilled. This is somewhat in disagreement with experiments where only enhanced magnetic properties have been reported. The possibility of metamagnetism in UMn2 is suggested. The bulk modulus for these Laves phase systems has been calculated. Total and partial densities-of-states are also reported.