Metamagnetism

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

Magnetocaloric effect and magnetic-field-induced shape recovery effect at room temperature in ferromagnetic Heusler alloy Ni-Mn-Sb

Abstract: The martensitic transition, magnetocaloric effect ( MCE) and shape memory effect ( MSE) of ferromagnetic Heusler alloys Ni50Mn50-x Sb-x (x = 12, 13 and 14) have been investigated. A large positive magnetic entropy change Delta SM was observed in the vicinity of the martensitic transition. The maximum value of Delta SM is 9.1 J kg(-1) K-1 in Ni50Mn37Sb13 at 287K for a magnetic field change of 5 T. This change originates from the first-order transition from a low-temperature weak-magnetic martensitic phase to a high-temperature ferromagnetic parent phase. A magnetic-field-induced shape recovery strain of about 15 ppm at room temperature and at a relatively low magnetic field ( 1.2 T) was observed to accompany the reverse martensitic transformation. The large field-induced MCE and MSE in the NiMnSb system make it a promising material for room-temperature application.

Metamagnetism, giant magnetoresistance and magnetocaloric effects in RCo2-based compounds in the vicinity of the Curie temperature

Abstract: Magnetisation and magnetoresistance isotherms were measured for a number of (R,R′)Co2, (R,Y)Co2 and R(Co,Si)2 (R,R′=rare earth) compounds. A metamagnetic transition is observed just above the Curie temperature (TC) of compounds having a first order phase transition, i.e. ErCo2-, HoCo2-, and DyCo2-based ones. Both 4f- and 3d-sublattice magnetic moments contribute to a sharp change of the magnetisation at this transition. The concurring suppression of the magnetoresistance can be considered to be due to quenching of spin fluctuations. In addition, the magnetic entropy change ΔSm is estimated from the magnetisation data by using a Maxwell equation. The resulting giant magnetocaloric effects are discussed in terms of the 4f(R)-localised spin and the 3d(Co)-spin fluctuations as well as the nature of the phase transition.

Coexistence of Spin-Canting, Metamagnetism, and Spin-Flop in a (4,4) Layered Manganese Azide Polymer

Abstract: A novel molecule-based magnetic polymer Mn(N3)2(btr)2 1 (btr = 4,4‘-bi-1,2,4-triazole) was synthesized and characterized crystallographically and magnetically. 1 crystallizes in the monoclinic system, space group P21/c, formula C8H8N18Mn, with a = 12.2831(4) A, b = 6.3680(1) A, c = 10.2245(3) A, β = 105.064(1)°, and Z = 2. Bridged by end-to-end azides, the Mn2+ ions form a two-dimensional layer with (4,4) topology; the layers are further connected to the three-dimensional network by the weak hydrogen bonds between ligands of btr. Magnetic studies on a polycrystalline sample show the existence of strong antiferromagnetic couplings between the adjacent Mn2+ ions, and the Neel temperature is TN = 23.7 K. In the ordered state below TN, detailed investigations on an oriented single-crystal sample of 1 reveal that the hidden spin-canting, metamagnetic transition, and spin-flop transition can appear in different circumstances. The ground state is of an antiferromagnet with hidden spin-canting. An external field ...

Giant entropy change at the co-occurrence of structural and magnetic transitions in the Ni2.19Mn0.81Ga Heusler alloy

Abstract: We have studied the isothermal entropy change around a first-order structural transformation and in correspondence to the second-order Curie transition in the ferromagnetic Heusler alloy Ni2.15Mn0.85Ga. The results have been compared with those obtained for the composition Ni2.19Mn0.81Ga, in which the martensitic structural transformation and the magnetic transition occur simultaneously. With a magnetic field span from 0 to 1.6 T, the magnetic entropy change reaches the value of 20 J/kg K when transitions are co-occurring, while 5 J/kg K is found when the only structural transition occurs.